| Message ID | 20230310130815.562418-1-alexander.sverdlin@siemens.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3] i2c: lpi2c: cache peripheral clock rate | expand |
Hi, sorry for the delay. Am Freitag, 10. März 2023, 14:08:15 CEST schrieb A. Sverdlin: > From: Alexander Sverdlin <alexander.sverdlin@siemens.com> > > One of the reasons to do it is to save some CPU cycles on cpu_freq_get() > under mutex. The second reason if the (false-positive) lockdep splat caused > by the recursive feature of the "prepare_lock" (one clock instance is I2C > peripheral clock and another is pcf85063 RTC as clock provider): > > ====================================================== > WARNING: possible circular locking dependency detected > 5.15.71+... #1 Tainted: G O > ------------------------------------------------------ > fs-value/2332 is trying to acquire lock: > ffff8000096cae08 (prepare_lock){+.+.}-{3:3}, at: clk_prepare_lock > > but task is already holding lock: > ffff000011021100 (i2c_register_adapter){+.+.}-{3:3}, at: > i2c_adapter_lock_bus > > which lock already depends on the new lock. > > the existing dependency chain (in reverse order) is: > > -> #2 (i2c_register_adapter){+.+.}-{3:3}: > lock_acquire > rt_mutex_lock_nested > i2c_adapter_lock_bus > i2c_transfer > regmap_i2c_read > _regmap_raw_read > _regmap_bus_read > _regmap_read > regmap_read > pcf85063_probe > i2c_device_probe > really_probe > __driver_probe_device > driver_probe_device > __device_attach_driver > bus_for_each_drv > __device_attach > device_initial_probe > bus_probe_device > device_add > device_register > i2c_new_client_device > of_i2c_register_devices > i2c_register_adapter > __i2c_add_numbered_adapter > i2c_add_adapter > lpi2c_imx_probe > platform_probe > really_probe > __driver_probe_device > driver_probe_device > __device_attach_driver > bus_for_each_drv > __device_attach > device_initial_probe > bus_probe_device > deferred_probe_work_func > process_one_work > worker_thread > kthread > ret_from_fork > > -> #1 (rtc_pcf85063:560:(&config->regmap)->lock){+.+.}-{3:3}: > lock_acquire > __mutex_lock > mutex_lock_nested > regmap_lock_mutex > regmap_read > pcf85063_clkout_recalc_rate > __clk_register > devm_clk_register > pcf85063_probe > i2c_device_probe > really_probe > __driver_probe_device > driver_probe_device > __device_attach_driver > bus_for_each_drv > __device_attach > device_initial_probe > bus_probe_device > device_add > device_register > i2c_new_client_device > of_i2c_register_devices > i2c_register_adapter > __i2c_add_numbered_adapter > i2c_add_adapter > lpi2c_imx_probe > platform_probe > really_probe > __driver_probe_device > driver_probe_device > __device_attach_driver > bus_for_each_drv > __device_attach > device_initial_probe > bus_probe_device > deferred_probe_work_func > process_one_work > worker_thread > kthread > ret_from_fork > > -> #0 (prepare_lock){+.+.}-{3:3}: > __lock_acquire > lock_acquire.part.0 > lock_acquire > __mutex_lock > mutex_lock_nested > clk_prepare_lock > clk_get_rate > lpi2c_imx_xfer > __i2c_transfer > i2c_transfer > regmap_i2c_read > _regmap_raw_read > regmap_raw_read > regmap_bulk_read > at24_read > nvmem_reg_read > bin_attr_nvmem_read > sysfs_kf_bin_read > kernfs_fop_read_iter > new_sync_read > vfs_read > ksys_read > __arm64_sys_read > invoke_syscall > ... > > other info that might help us debug this: > > Chain exists of: > prepare_lock --> rtc_pcf85063:560:(&config->regmap)->lock --> > i2c_register_adapter > > Possible unsafe locking scenario: > > CPU0 CPU1 > ---- ---- > lock(i2c_register_adapter); > > lock(rtc_pcf85063:560:(&config->regmap)->lock); lock(i2c_register_adapter); > lock(prepare_lock); > > *** DEADLOCK *** > > 4 locks held by .../2332: > #0: ffff0000146eb288 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_read_iter > #1: ffff000010fe4400 (kn->active#72){.+.+}-{0:0}, at: kernfs_fop_read_iter > #2: ffff0000110168e8 (&at24->lock){+.+.}-{3:3}, at: at24_read > #3: ffff000011021100 (i2c_register_adapter){+.+.}-{3:3}, at: > i2c_adapter_lock_bus > > stack backtrace: > CPU: 1 PID: 2332 Comm: ... Tainted: G O 5.15.71+... #1 > Hardware name: ... (DT) > Call trace: > dump_backtrace > show_stack > dump_stack_lvl > dump_stack > print_circular_bug > check_noncircular > __lock_acquire > lock_acquire.part.0 > lock_acquire > __mutex_lock > mutex_lock_nested > clk_prepare_lock > clk_get_rate > lpi2c_imx_xfer > __i2c_transfer > i2c_transfer > regmap_i2c_read > _regmap_raw_read > regmap_raw_read > regmap_bulk_read > at24_read > nvmem_reg_read > bin_attr_nvmem_read > sysfs_kf_bin_read > kernfs_fop_read_iter > new_sync_read > vfs_read > ksys_read > __arm64_sys_read > invoke_syscall > ... > > Fixes: a55fa9d0e42e ("i2c: imx-lpi2c: add low power i2c bus driver") > Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com> > --- > drivers/i2c/busses/i2c-imx-lpi2c.c | 33 +++++++++++++++++++++++++++--- > 1 file changed, 30 insertions(+), 3 deletions(-) > > Changelog: > v3: fixed build error reported by kernel test robot <lkp@intel.com> > > https://lore.kernel.org/oe-kbuild-all/202303102010.pAv56wKs-lkp@intel.com/ > v2: added clk_notifier as Alexander suggested > > diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c > b/drivers/i2c/busses/i2c-imx-lpi2c.c index 188f2a36d2fd6..5f1d1d4e018bd > 100644 > --- a/drivers/i2c/busses/i2c-imx-lpi2c.c > +++ b/drivers/i2c/busses/i2c-imx-lpi2c.c > @@ -100,6 +100,8 @@ struct lpi2c_imx_struct { > __u8 *rx_buf; > __u8 *tx_buf; > struct completion complete; > + struct notifier_block clk_change_nb; > + unsigned int rate_per; > unsigned int msglen; > unsigned int delivered; > unsigned int block_data; > @@ -198,24 +200,37 @@ static void lpi2c_imx_stop(struct lpi2c_imx_struct > *lpi2c_imx) } while (1); > } > > +static int lpi2c_imx_clk_change_cb(struct notifier_block *nb, > + unsigned long action, void *data) > +{ > + struct clk_notifier_data *ndata = data; > + struct lpi2c_imx_struct *lpi2c_imx = container_of(nb, > + struct lpi2c_imx_struct, > + clk_change_nb); > + > + if (action & POST_RATE_CHANGE) > + lpi2c_imx->rate_per = ndata->new_rate; > + > + return NOTIFY_OK; > +} > + > /* CLKLO = I2C_CLK_RATIO * CLKHI, SETHOLD = CLKHI, DATAVD = CLKHI/2 */ > static int lpi2c_imx_config(struct lpi2c_imx_struct *lpi2c_imx) > { > u8 prescale, filt, sethold, clkhi, clklo, datavd; > - unsigned int clk_rate, clk_cycle; > + unsigned int clk_cycle; > enum lpi2c_imx_pincfg pincfg; > unsigned int temp; > > lpi2c_imx_set_mode(lpi2c_imx); > > - clk_rate = clk_get_rate(lpi2c_imx->clks[0].clk); > if (lpi2c_imx->mode == HS || lpi2c_imx->mode == ULTRA_FAST) > filt = 0; > else > filt = 2; > > for (prescale = 0; prescale <= 7; prescale++) { > - clk_cycle = clk_rate / ((1 << prescale) * lpi2c_imx- >bitrate) > + clk_cycle = lpi2c_imx->rate_per / ((1 << prescale) * lpi2c_imx->bitrate) > - 3 - (filt >> 1); > clkhi = (clk_cycle + I2C_CLK_RATIO) / (I2C_CLK_RATIO + 1); > clklo = clk_cycle - clkhi; > @@ -588,6 +603,18 @@ static int lpi2c_imx_probe(struct platform_device > *pdev) if (ret) > return ret; > > + lpi2c_imx->clk_change_nb.notifier_call = lpi2c_imx_clk_change_cb; > + ret = devm_clk_notifier_register(&pdev->dev, lpi2c_imx->clks[0].clk, > + &lpi2c_imx->clk_change_nb); > + if (ret) > + return dev_err_probe(&pdev->dev, ret, > + "can't register peripheral clock notifier\n"); > + lpi2c_imx->rate_per = clk_get_rate(lpi2c_imx->clks[0].clk); > + if (!lpi2c_imx->rate_per) { > + dev_err(&pdev->dev, "can't get I2C peripheral clock rate\n"); > + return -EINVAL; > + } > + I would switch the order of the calls to devm_clk_notifier_register() and clk_get_rate(). AFAICS this looks like a possible lost update. The notifier might change rate_per before the (old) value from clk_get_rate is actually assigned. With this change you fix the following call chain (from a kernel log) [ 4.562396] clk_prepare_lock+0x48/0x9c [ 4.566740] clk_get_rate+0x1c/0x74 [ 4.570736] lpi2c_imx_config+0x4c/0x190 [ 4.575167] lpi2c_imx_master_enable+0x54/0x128 [ 4.580205] lpi2c_imx_xfer+0x2c/0x3c8 Unfortuantely this was just hiding another call path from lpi2c_imx_xfer to clk_bulk_prepare. Here is my kernel log: [ 22.264508] ====================================================== [ 22.270697] WARNING: possible circular locking dependency detected [ 22.276893] 6.3.0-rc7-next-20230420+ #6 Not tainted [ 22.281782] ------------------------------------------------------ [ 22.287968] kworker/2:3/93 is trying to acquire lock: [ 22.293034] ffff800009d38bf8 (prepare_lock){+.+.}-{3:3}, at: clk_prepare_lock+0x48/0x9c [ 22.301095] [ 22.301095] but task is already holding lock: [ 22.306942] ffff0000039ab100 (i2c_register_adapter){+.+.}-{3:3}, at: i2c_adapter_lock_bus+0x20/0x2c [ 22.316046] [ 22.316046] which lock already depends on the new lock. [ 22.316046] [ 22.324238] [ 22.324238] the existing dependency chain (in reverse order) is: [ 22.331727] [ 22.331727] -> #2 (i2c_register_adapter){+.+.}-{3:3}: [ 22.338295] __lock_acquire+0x370/0x6e8 [ 22.342674] lock_acquire.part.0+0xcc/0x208 [ 22.347399] lock_acquire+0x94/0x14c [ 22.351509] rt_mutex_lock_nested+0x5c/0x98 [ 22.356235] i2c_adapter_lock_bus+0x20/0x2c [ 22.360961] i2c_transfer+0x80/0x114 [ 22.365069] regmap_i2c_read+0x5c/0xa0 [ 22.369362] _regmap_raw_read+0x110/0x2dc [ 22.373905] _regmap_bus_read+0x40/0x74 [ 22.378274] _regmap_read+0x74/0x248 [ 22.382393] regmap_read+0x48/0x70 [ 22.386337] pcf85063_probe+0xf0/0x4f4 [ 22.390640] i2c_device_probe+0x100/0x2d4 [ 22.395206] call_driver_probe+0x28/0x15c [ 22.399750] really_probe+0x180/0x320 [ 22.403946] __driver_probe_device+0x84/0x144 [ 22.408837] driver_probe_device+0x38/0x150 [ 22.413554] __device_attach_driver+0xcc/0x194 [ 22.418532] bus_for_each_drv+0x80/0xdc [ 22.422910] __device_attach+0xa8/0x1f8 [ 22.426545] systemd-journald[128]: Oldest entry in /var/log/journal/ e4579cc7db6747028247b9b859e132d6/system.joural is older than the configured file retention duration (1month), suggesting rotation. [ 22.427278] device_initial_probe+0x10/0x18 [ 22.427290] bus_probe_device+0xa4/0xa8 [ 22.427299] device_add+0x3b0/0x508 [ 22.427311] device_register+0x1c/0x28 [ 22.427323] i2c_new_client_device+0x1c8/0x2bc [ 22.427333] of_i2c_register_device+0xb4/0xdc [ 22.427344] of_i2c_register_devices+0x80/0x154 [ 22.456329] systemd-journald[128]: /var/log/journal/ e4579cc7db6747028247b9b859e132d6/system.journal: Journal heaer limits reached or header out-of-date, rotating. [ 22.458176] i2c_register_adapter+0x184/0x4c8 [ 22.458202] __i2c_add_numbered_adapter+0x5c/0xa4 [ 22.502097] i2c_add_adapter+0xa0/0xcc [ 22.502122] lpi2c_imx_probe+0x23c/0x350 [ 22.502135] platform_probe+0x64/0xfc [ 22.502146] call_driver_probe+0x28/0x15c [ 22.502155] really_probe+0x180/0x320 [ 22.502164] __driver_probe_device+0x84/0x144 [ 22.502173] driver_probe_device+0x38/0x150 [ 22.502182] __device_attach_driver+0xcc/0x194 [ 22.502191] bus_for_each_drv+0x80/0xdc [ 22.502204] __device_attach+0xa8/0x1f8 [ 22.502212] device_initial_probe+0x10/0x18 [ 22.502222] bus_probe_device+0xa4/0xa8 [ 22.502230] deferred_probe_work_func+0xa0/0xf0 [ 22.502239] process_one_work+0x284/0x5b0 [ 22.502252] worker_thread+0x68/0x39c [ 22.502263] kthread+0x104/0x108 [ 22.502274] ret_from_fork+0x10/0x20 [ 22.502286] [ 22.502286] -> #1 (rtc_pcf85063:594:(&config->regmap)->lock){+.+.}-{3:3}: [ 22.502310] __lock_acquire+0x370/0x6e8 [ 22.502322] lock_acquire.part.0+0xcc/0x208 [ 22.502332] lock_acquire+0x94/0x14c [ 22.502341] __mutex_lock+0x9c/0x838 [ 22.502353] mutex_lock_nested+0x20/0x28 [ 22.502364] regmap_lock_mutex+0x10/0x18 [ 22.502377] regmap_read+0x38/0x70 [ 22.502389] pcf85063_clkout_recalc_rate+0x2c/0x78 [ 22.502403] __clk_core_init+0x46c/0x4e0 [ 22.502417] __clk_register+0x160/0x23c [ 22.502429] devm_clk_register+0x58/0xb4 [ 22.502441] pcf85063_probe+0x238/0x4f4 [ 22.502451] i2c_device_probe+0x100/0x2d4 [ 22.502465] call_driver_probe+0x28/0x15c [ 22.502473] really_probe+0x180/0x320 [ 22.502482] __driver_probe_device+0x84/0x144 [ 22.502491] driver_probe_device+0x38/0x150 [ 22.502500] __device_attach_driver+0xcc/0x194 [ 22.502509] bus_for_each_drv+0x80/0xdc [ 22.502521] __device_attach+0xa8/0x1f8 [ 22.502530] device_initial_probe+0x10/0x18 [ 22.502539] bus_probe_device+0xa4/0xa8 [ 22.502548] device_add+0x3b0/0x508 [ 22.502559] device_register+0x1c/0x28 [ 22.502570] i2c_new_client_device+0x1c8/0x2bc [ 22.502580] of_i2c_register_device+0xb4/0xdc [ OK ] Started Network Time Synchronization[ 22.502589] of_i2c_register_devices+0x80/0x154 .[ 22.502599] i2c_register_adapter+0x184/0x4c8 [ 22.502607] __i2c_add_numbered_adapter+0x5c/0xa4 [ 22.502616] i2c_add_adapter+0xa0/0xcc [ 22.502624] lpi2c_imx_probe+0x23c/0x350 [ 22.502636] platform_probe+0x64/0xfc [ 22.502646] call_driver_probe+0x28/0x15c [ 22.502655] really_probe+0x180/0x320 [ 22.502663] __driver_probe_device+0x84/0x144 [ 22.502672] driver_probe_device+0x38/0x150 [ 22.502681] __device_attach_driver+0xcc/0x194 [ 22.502690] bus_for_each_drv+0x80/0xdc [ 22.502702] __device_attach+0xa8/0x1f8 [ 22.502711] device_initial_probe+0x10/0x18 [ 22.502720] bus_probe_device+0xa4/0xa8 [ 22.502729] deferred_probe_work_func+0xa0/0xf0 [ 22.502738] process_one_work+0x284/0x5b0 [ 22.502749] worker_thread+0x68/0x39c [ 22.502760] kthread+0x104/0x108 [ 22.502770] ret_from_fork+0x10/0x20 [ 22.502779] [ 22.502779] -> #0 (prepare_lock){+.+.}-{3:3}: [ 22.502799] check_prev_add+0xb0/0xc80 [ 22.502809] validate_chain+0x444/0x510 [ 22.502818] __lock_acquire+0x370/0x6e8 [ 22.502827] lock_acquire.part.0+0xcc/0x208 [ 22.502837] lock_acquire+0x94/0x14c [ 22.502846] __mutex_lock+0x9c/0x838 [ 22.502857] mutex_lock_nested+0x20/0x28 [ 22.502867] clk_prepare_lock+0x48/0x9c [ 22.502878] clk_prepare+0x1c/0x3c [ 22.502890] clk_bulk_prepare+0x48/0xcc [ 22.502899] lpi2c_runtime_resume+0x30/0x84 [ 22.502910] pm_generic_runtime_resume+0x28/0x3c [ 22.502923] __genpd_runtime_resume+0x2c/0xa0 [ 22.502935] genpd_runtime_resume+0xbc/0x308 [ 22.502944] __rpm_callback+0x44/0x19c [ 22.502953] rpm_callback+0x64/0x70 [ 22.502962] rpm_resume+0x438/0x6d8 [ 22.502970] __pm_runtime_resume+0x54/0xb0 [ 22.502978] lpi2c_imx_master_enable+0x24/0x128 [ 22.502989] lpi2c_imx_xfer+0x2c/0x3c8 [ 22.502999] __i2c_transfer+0xe4/0x5a0 [ 22.503008] i2c_transfer+0x90/0x114 [ 22.503016] i2c_transfer_buffer_flags+0x58/0x84 [ 22.503025] regmap_i2c_write+0x1c/0x4c [ 22.503035] _regmap_raw_write_impl+0x7dc/0x944 [ 22.503044] _regmap_bus_raw_write+0x5c/0x74 [ 22.503052] _regmap_write+0x64/0x238 [ 22.503060] _regmap_update_bits+0x100/0x11c [ 22.503069] regmap_update_bits_base+0x60/0x90 [ 22.503077] pca953x_gpio_set_value+0x74/0x90 [ 22.503088] gpiod_set_raw_value_commit+0x6c/0x7c [ 22.503098] gpiod_set_value_nocheck+0x68/0x70 [ 22.503107] gpiod_set_value_cansleep+0x3c/0xa8 [ 22.503116] gpio_led_set_blocking+0x54/0x7c [ 22.503128] set_brightness_delayed+0x90/0xd8 [ 22.503138] process_one_work+0x284/0x5b0 [ 22.503149] worker_thread+0x68/0x39c [ 22.503160] kthread+0x104/0x108 [ 22.503169] ret_from_fork+0x10/0x20 [ 22.503179] [ 22.503179] other info that might help us debug this: [ 22.503179] [ 22.503183] Chain exists of: [ 22.503183] prepare_lock --> rtc_pcf85063:594:(&config->regmap)->lock --> i2c_register_adapter [ 22.503183] [ 22.503207] Possible unsafe locking scenario: [ 22.503207] [ 22.503210] CPU0 CPU1 [ 22.503213] ---- ---- [ 22.503216] lock(i2c_register_adapter); [ 22.503225] lock(rtc_pcf85063:594:(&config- >regmap)->lock); [ 22.503235] lock(i2c_register_adapter); [ 22.503244] lock(prepare_lock); [ 22.503253] [ 22.503253] *** DEADLOCK *** Now lpi2c_runtime_resume will call into clk_prepare() which also calls clk_prepare_lock() (identical to clk_get_rate). Best regards, Alexader > pm_runtime_set_autosuspend_delay(&pdev->dev, I2C_PM_TIMEOUT); > pm_runtime_use_autosuspend(&pdev->dev); > pm_runtime_get_noresume(&pdev->dev);
On 21.04.2023 15:48:59, Alexander Stein wrote: [...] > Now lpi2c_runtime_resume will call into clk_prepare() which also calls > clk_prepare_lock() (identical to clk_get_rate). IIRC this is a general problem^w limitation of the clock framework, clock providers cannot use clocks themselves in certain callback, e.g. set_rate. Marc
Hello Alexander, thanks for looking into that! On Fri, 2023-04-21 at 15:48 +0200, Alexander Stein wrote: > Unfortuantely this was just hiding another call path from > lpi2c_imx_xfer to > clk_bulk_prepare. Here is my kernel log: Yes, soon after publishing the patch I reproduced your log as well, that's why I didn't follow up on the original patch, as it indeed doesn't solve all the LOCKDEP splats with lpi2c involved and I didn't have time to look into this yet. > [ 22.264508] ====================================================== > [ 22.270697] WARNING: possible circular locking dependency detected > [ 22.276893] 6.3.0-rc7-next-20230420+ #6 Not tainted > [ 22.281782] ------------------------------------------------------ > [ 22.287968] kworker/2:3/93 is trying to acquire lock: > [ 22.293034] ffff800009d38bf8 (prepare_lock){+.+.}-{3:3}, at: > clk_prepare_lock+0x48/0x9c > [ 22.301095] > [ 22.301095] but task is already holding lock: > [ 22.306942] ffff0000039ab100 (i2c_register_adapter){+.+.}-{3:3}, > at: > i2c_adapter_lock_bus+0x20/0x2c > [ 22.316046] > [ 22.316046] which lock already depends on the new lock. > [ 22.316046] > [ 22.324238] > [ 22.324238] the existing dependency chain (in reverse order) is: > [ 22.331727] > [ 22.331727] -> #2 (i2c_register_adapter){+.+.}-{3:3}: > [ 22.338295] __lock_acquire+0x370/0x6e8 > [ 22.342674] lock_acquire.part.0+0xcc/0x208 > [ 22.347399] lock_acquire+0x94/0x14c > [ 22.351509] rt_mutex_lock_nested+0x5c/0x98 > [ 22.356235] i2c_adapter_lock_bus+0x20/0x2c > [ 22.360961] i2c_transfer+0x80/0x114 > [ 22.365069] regmap_i2c_read+0x5c/0xa0 > [ 22.369362] _regmap_raw_read+0x110/0x2dc > [ 22.373905] _regmap_bus_read+0x40/0x74 > [ 22.378274] _regmap_read+0x74/0x248 > [ 22.382393] regmap_read+0x48/0x70 > [ 22.386337] pcf85063_probe+0xf0/0x4f4 > [ 22.390640] i2c_device_probe+0x100/0x2d4 > [ 22.395206] call_driver_probe+0x28/0x15c > [ 22.399750] really_probe+0x180/0x320 > [ 22.403946] __driver_probe_device+0x84/0x144 > [ 22.408837] driver_probe_device+0x38/0x150 > [ 22.413554] __device_attach_driver+0xcc/0x194 > [ 22.418532] bus_for_each_drv+0x80/0xdc > [ 22.422910] __device_attach+0xa8/0x1f8 > [ 22.426545] systemd-journald[128]: Oldest entry in > /var/log/journal/ > e4579cc7db6747028247b9b859e132d6/system.joural is older than the > configured > file retention duration (1month), suggesting rotation. > [ 22.427278] device_initial_probe+0x10/0x18 > [ 22.427290] bus_probe_device+0xa4/0xa8 > [ 22.427299] device_add+0x3b0/0x508 > [ 22.427311] device_register+0x1c/0x28 > [ 22.427323] i2c_new_client_device+0x1c8/0x2bc > [ 22.427333] of_i2c_register_device+0xb4/0xdc > [ 22.427344] of_i2c_register_devices+0x80/0x154 > [ 22.456329] systemd-journald[128]: /var/log/journal/ > e4579cc7db6747028247b9b859e132d6/system.journal: Journal heaer limits > reached > or header out-of-date, rotating. > [ 22.458176] i2c_register_adapter+0x184/0x4c8 > [ 22.458202] __i2c_add_numbered_adapter+0x5c/0xa4 > [ 22.502097] i2c_add_adapter+0xa0/0xcc > [ 22.502122] lpi2c_imx_probe+0x23c/0x350 > [ 22.502135] platform_probe+0x64/0xfc > [ 22.502146] call_driver_probe+0x28/0x15c > [ 22.502155] really_probe+0x180/0x320 > [ 22.502164] __driver_probe_device+0x84/0x144 > [ 22.502173] driver_probe_device+0x38/0x150 > [ 22.502182] __device_attach_driver+0xcc/0x194 > [ 22.502191] bus_for_each_drv+0x80/0xdc > [ 22.502204] __device_attach+0xa8/0x1f8 > [ 22.502212] device_initial_probe+0x10/0x18 > [ 22.502222] bus_probe_device+0xa4/0xa8 > [ 22.502230] deferred_probe_work_func+0xa0/0xf0 > [ 22.502239] process_one_work+0x284/0x5b0 > [ 22.502252] worker_thread+0x68/0x39c > [ 22.502263] kthread+0x104/0x108 > [ 22.502274] ret_from_fork+0x10/0x20 > [ 22.502286] > [ 22.502286] -> #1 (rtc_pcf85063:594:(&config->regmap)- > >lock){+.+.}-{3:3}: > [ 22.502310] __lock_acquire+0x370/0x6e8 > [ 22.502322] lock_acquire.part.0+0xcc/0x208 > [ 22.502332] lock_acquire+0x94/0x14c > [ 22.502341] __mutex_lock+0x9c/0x838 > [ 22.502353] mutex_lock_nested+0x20/0x28 > [ 22.502364] regmap_lock_mutex+0x10/0x18 > [ 22.502377] regmap_read+0x38/0x70 > [ 22.502389] pcf85063_clkout_recalc_rate+0x2c/0x78 > [ 22.502403] __clk_core_init+0x46c/0x4e0 > [ 22.502417] __clk_register+0x160/0x23c > [ 22.502429] devm_clk_register+0x58/0xb4 > [ 22.502441] pcf85063_probe+0x238/0x4f4 > [ 22.502451] i2c_device_probe+0x100/0x2d4 > [ 22.502465] call_driver_probe+0x28/0x15c > [ 22.502473] really_probe+0x180/0x320 > [ 22.502482] __driver_probe_device+0x84/0x144 > [ 22.502491] driver_probe_device+0x38/0x150 > [ 22.502500] __device_attach_driver+0xcc/0x194 > [ 22.502509] bus_for_each_drv+0x80/0xdc > [ 22.502521] __device_attach+0xa8/0x1f8 > [ 22.502530] device_initial_probe+0x10/0x18 > [ 22.502539] bus_probe_device+0xa4/0xa8 > [ 22.502548] device_add+0x3b0/0x508 > [ 22.502559] device_register+0x1c/0x28 > [ 22.502570] i2c_new_client_device+0x1c8/0x2bc > [ 22.502580] of_i2c_register_device+0xb4/0xdc > [ OK ] Started Network Time Synchronization[ 22.502589] > of_i2c_register_devices+0x80/0x154 > .[ 22.502599] i2c_register_adapter+0x184/0x4c8 > > [ 22.502607] __i2c_add_numbered_adapter+0x5c/0xa4 > [ 22.502616] i2c_add_adapter+0xa0/0xcc > [ 22.502624] lpi2c_imx_probe+0x23c/0x350 > [ 22.502636] platform_probe+0x64/0xfc > [ 22.502646] call_driver_probe+0x28/0x15c > [ 22.502655] really_probe+0x180/0x320 > [ 22.502663] __driver_probe_device+0x84/0x144 > [ 22.502672] driver_probe_device+0x38/0x150 > [ 22.502681] __device_attach_driver+0xcc/0x194 > [ 22.502690] bus_for_each_drv+0x80/0xdc > [ 22.502702] __device_attach+0xa8/0x1f8 > [ 22.502711] device_initial_probe+0x10/0x18 > [ 22.502720] bus_probe_device+0xa4/0xa8 > [ 22.502729] deferred_probe_work_func+0xa0/0xf0 > [ 22.502738] process_one_work+0x284/0x5b0 > [ 22.502749] worker_thread+0x68/0x39c > [ 22.502760] kthread+0x104/0x108 > [ 22.502770] ret_from_fork+0x10/0x20 > [ 22.502779] > [ 22.502779] -> #0 (prepare_lock){+.+.}-{3:3}: > [ 22.502799] check_prev_add+0xb0/0xc80 > [ 22.502809] validate_chain+0x444/0x510 > [ 22.502818] __lock_acquire+0x370/0x6e8 > [ 22.502827] lock_acquire.part.0+0xcc/0x208 > [ 22.502837] lock_acquire+0x94/0x14c > [ 22.502846] __mutex_lock+0x9c/0x838 > [ 22.502857] mutex_lock_nested+0x20/0x28 > [ 22.502867] clk_prepare_lock+0x48/0x9c > [ 22.502878] clk_prepare+0x1c/0x3c > [ 22.502890] clk_bulk_prepare+0x48/0xcc > [ 22.502899] lpi2c_runtime_resume+0x30/0x84 > [ 22.502910] pm_generic_runtime_resume+0x28/0x3c > [ 22.502923] __genpd_runtime_resume+0x2c/0xa0 > [ 22.502935] genpd_runtime_resume+0xbc/0x308 > [ 22.502944] __rpm_callback+0x44/0x19c > [ 22.502953] rpm_callback+0x64/0x70 > [ 22.502962] rpm_resume+0x438/0x6d8 > [ 22.502970] __pm_runtime_resume+0x54/0xb0 > [ 22.502978] lpi2c_imx_master_enable+0x24/0x128 > [ 22.502989] lpi2c_imx_xfer+0x2c/0x3c8 > [ 22.502999] __i2c_transfer+0xe4/0x5a0 > [ 22.503008] i2c_transfer+0x90/0x114 > [ 22.503016] i2c_transfer_buffer_flags+0x58/0x84 > [ 22.503025] regmap_i2c_write+0x1c/0x4c > [ 22.503035] _regmap_raw_write_impl+0x7dc/0x944 > [ 22.503044] _regmap_bus_raw_write+0x5c/0x74 > [ 22.503052] _regmap_write+0x64/0x238 > [ 22.503060] _regmap_update_bits+0x100/0x11c > [ 22.503069] regmap_update_bits_base+0x60/0x90 > [ 22.503077] pca953x_gpio_set_value+0x74/0x90 > [ 22.503088] gpiod_set_raw_value_commit+0x6c/0x7c > [ 22.503098] gpiod_set_value_nocheck+0x68/0x70 > [ 22.503107] gpiod_set_value_cansleep+0x3c/0xa8 > [ 22.503116] gpio_led_set_blocking+0x54/0x7c > [ 22.503128] set_brightness_delayed+0x90/0xd8 > [ 22.503138] process_one_work+0x284/0x5b0 > [ 22.503149] worker_thread+0x68/0x39c > [ 22.503160] kthread+0x104/0x108 > [ 22.503169] ret_from_fork+0x10/0x20 > [ 22.503179] > [ 22.503179] other info that might help us debug this: > [ 22.503179] > [ 22.503183] Chain exists of: > [ 22.503183] prepare_lock --> rtc_pcf85063:594:(&config->regmap)- > >lock --> > i2c_register_adapter > [ 22.503183] > [ 22.503207] Possible unsafe locking scenario: > [ 22.503207] > [ 22.503210] CPU0 CPU1 > [ 22.503213] ---- ---- > [ 22.503216] lock(i2c_register_adapter); > [ 22.503225] > lock(rtc_pcf85063:594:(&config- > > regmap)->lock); > [ 22.503235] > lock(i2c_register_adapter); > [ 22.503244] lock(prepare_lock); > [ 22.503253] > [ 22.503253] *** DEADLOCK *** > > Now lpi2c_runtime_resume will call into clk_prepare() which also > calls > clk_prepare_lock() (identical to clk_get_rate).
Hi Marc, Am Freitag, 21. April 2023, 15:59:52 CEST schrieb Marc Kleine-Budde: > * PGP Signed by an unknown key > > On 21.04.2023 15:48:59, Alexander Stein wrote: > [...] > > > Now lpi2c_runtime_resume will call into clk_prepare() which also calls > > clk_prepare_lock() (identical to clk_get_rate). > > IIRC this is a general problem^w limitation of the clock framework, > clock providers cannot use clocks themselves in certain callback, e.g. > set_rate. Well, that's essentially impossible when this clock provider is attached via i2c. i2c transfers potentially need to change or prepare clocks. One problem is that during clock registration (__clk_core_init) in the call to clk_ops.recalc_rate an i2c transfer is issued (via regmap). This is the inverse lock order to a regular transfer runtime resuming the i2c master and preparing the clocks. While looking at this, is_prepared is also affected by this. It's reading a register, thus issuing a i2c transfer. But this function can also be called from within clk_unprepare_unused_subtree, which holds clk_prepare_lock as well. This might be avoided by using regcache, but I'm not really sure this catches every case. Best regards, Alexander
Am Freitag, 10. März 2023, 14:08:15 CEST schrieb A. Sverdlin: > From: Alexander Sverdlin <alexander.sverdlin@siemens.com> > > One of the reasons to do it is to save some CPU cycles on cpu_freq_get() > under mutex. The second reason if the (false-positive) lockdep splat caused > by the recursive feature of the "prepare_lock" (one clock instance is I2C > peripheral clock and another is pcf85063 RTC as clock provider): > > ====================================================== > WARNING: possible circular locking dependency detected > 5.15.71+... #1 Tainted: G O > ------------------------------------------------------ > fs-value/2332 is trying to acquire lock: > ffff8000096cae08 (prepare_lock){+.+.}-{3:3}, at: clk_prepare_lock > > but task is already holding lock: > ffff000011021100 (i2c_register_adapter){+.+.}-{3:3}, at: > i2c_adapter_lock_bus > > which lock already depends on the new lock. > > the existing dependency chain (in reverse order) is: > > -> #2 (i2c_register_adapter){+.+.}-{3:3}: > lock_acquire > rt_mutex_lock_nested > i2c_adapter_lock_bus > i2c_transfer > regmap_i2c_read > _regmap_raw_read > _regmap_bus_read > _regmap_read > regmap_read > pcf85063_probe > i2c_device_probe > really_probe > __driver_probe_device > driver_probe_device > __device_attach_driver > bus_for_each_drv > __device_attach > device_initial_probe > bus_probe_device > device_add > device_register > i2c_new_client_device > of_i2c_register_devices > i2c_register_adapter > __i2c_add_numbered_adapter > i2c_add_adapter > lpi2c_imx_probe > platform_probe > really_probe > __driver_probe_device > driver_probe_device > __device_attach_driver > bus_for_each_drv > __device_attach > device_initial_probe > bus_probe_device > deferred_probe_work_func > process_one_work > worker_thread > kthread > ret_from_fork > > -> #1 (rtc_pcf85063:560:(&config->regmap)->lock){+.+.}-{3:3}: > lock_acquire > __mutex_lock > mutex_lock_nested > regmap_lock_mutex > regmap_read > pcf85063_clkout_recalc_rate > __clk_register > devm_clk_register > pcf85063_probe > i2c_device_probe > really_probe > __driver_probe_device > driver_probe_device > __device_attach_driver > bus_for_each_drv > __device_attach > device_initial_probe > bus_probe_device > device_add > device_register > i2c_new_client_device > of_i2c_register_devices > i2c_register_adapter > __i2c_add_numbered_adapter > i2c_add_adapter > lpi2c_imx_probe > platform_probe > really_probe > __driver_probe_device > driver_probe_device > __device_attach_driver > bus_for_each_drv > __device_attach > device_initial_probe > bus_probe_device > deferred_probe_work_func > process_one_work > worker_thread > kthread > ret_from_fork > > -> #0 (prepare_lock){+.+.}-{3:3}: > __lock_acquire > lock_acquire.part.0 > lock_acquire > __mutex_lock > mutex_lock_nested > clk_prepare_lock > clk_get_rate > lpi2c_imx_xfer > __i2c_transfer > i2c_transfer > regmap_i2c_read > _regmap_raw_read > regmap_raw_read > regmap_bulk_read > at24_read > nvmem_reg_read > bin_attr_nvmem_read > sysfs_kf_bin_read > kernfs_fop_read_iter > new_sync_read > vfs_read > ksys_read > __arm64_sys_read > invoke_syscall > ... > > other info that might help us debug this: > > Chain exists of: > prepare_lock --> rtc_pcf85063:560:(&config->regmap)->lock --> > i2c_register_adapter > > Possible unsafe locking scenario: > > CPU0 CPU1 > ---- ---- > lock(i2c_register_adapter); > > lock(rtc_pcf85063:560:(&config->regmap)->lock); lock(i2c_register_adapter); > lock(prepare_lock); > > *** DEADLOCK *** > > 4 locks held by .../2332: > #0: ffff0000146eb288 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_read_iter > #1: ffff000010fe4400 (kn->active#72){.+.+}-{0:0}, at: kernfs_fop_read_iter > #2: ffff0000110168e8 (&at24->lock){+.+.}-{3:3}, at: at24_read > #3: ffff000011021100 (i2c_register_adapter){+.+.}-{3:3}, at: > i2c_adapter_lock_bus > > stack backtrace: > CPU: 1 PID: 2332 Comm: ... Tainted: G O 5.15.71+... #1 > Hardware name: ... (DT) > Call trace: > dump_backtrace > show_stack > dump_stack_lvl > dump_stack > print_circular_bug > check_noncircular > __lock_acquire > lock_acquire.part.0 > lock_acquire > __mutex_lock > mutex_lock_nested > clk_prepare_lock > clk_get_rate > lpi2c_imx_xfer > __i2c_transfer > i2c_transfer > regmap_i2c_read > _regmap_raw_read > regmap_raw_read > regmap_bulk_read > at24_read > nvmem_reg_read > bin_attr_nvmem_read > sysfs_kf_bin_read > kernfs_fop_read_iter > new_sync_read > vfs_read > ksys_read > __arm64_sys_read > invoke_syscall > ... > > Fixes: a55fa9d0e42e ("i2c: imx-lpi2c: add low power i2c bus driver") > Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com> Reviewed-by: Alexander Stein <alexander.stein@ew.tq-group.com> Note: [1] needs to be applied as well in order to get rid of all the lockdep errors. [1] https://lore.kernel.org/linux-i2c/20230424080627.20564-1-alexander.stein@ew.tq-group.com/T/#u > --- > drivers/i2c/busses/i2c-imx-lpi2c.c | 33 +++++++++++++++++++++++++++--- > 1 file changed, 30 insertions(+), 3 deletions(-) > > Changelog: > v3: fixed build error reported by kernel test robot <lkp@intel.com> > > https://lore.kernel.org/oe-kbuild-all/202303102010.pAv56wKs-lkp@intel.com/ > v2: added clk_notifier as Alexander suggested > > diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c > b/drivers/i2c/busses/i2c-imx-lpi2c.c index 188f2a36d2fd6..5f1d1d4e018bd > 100644 > --- a/drivers/i2c/busses/i2c-imx-lpi2c.c > +++ b/drivers/i2c/busses/i2c-imx-lpi2c.c > @@ -100,6 +100,8 @@ struct lpi2c_imx_struct { > __u8 *rx_buf; > __u8 *tx_buf; > struct completion complete; > + struct notifier_block clk_change_nb; > + unsigned int rate_per; > unsigned int msglen; > unsigned int delivered; > unsigned int block_data; > @@ -198,24 +200,37 @@ static void lpi2c_imx_stop(struct lpi2c_imx_struct > *lpi2c_imx) } while (1); > } > > +static int lpi2c_imx_clk_change_cb(struct notifier_block *nb, > + unsigned long action, void *data) > +{ > + struct clk_notifier_data *ndata = data; > + struct lpi2c_imx_struct *lpi2c_imx = container_of(nb, > + struct lpi2c_imx_struct, > + clk_change_nb); > + > + if (action & POST_RATE_CHANGE) > + lpi2c_imx->rate_per = ndata->new_rate; > + > + return NOTIFY_OK; > +} > + > /* CLKLO = I2C_CLK_RATIO * CLKHI, SETHOLD = CLKHI, DATAVD = CLKHI/2 */ > static int lpi2c_imx_config(struct lpi2c_imx_struct *lpi2c_imx) > { > u8 prescale, filt, sethold, clkhi, clklo, datavd; > - unsigned int clk_rate, clk_cycle; > + unsigned int clk_cycle; > enum lpi2c_imx_pincfg pincfg; > unsigned int temp; > > lpi2c_imx_set_mode(lpi2c_imx); > > - clk_rate = clk_get_rate(lpi2c_imx->clks[0].clk); > if (lpi2c_imx->mode == HS || lpi2c_imx->mode == ULTRA_FAST) > filt = 0; > else > filt = 2; > > for (prescale = 0; prescale <= 7; prescale++) { > - clk_cycle = clk_rate / ((1 << prescale) * lpi2c_imx- >bitrate) > + clk_cycle = lpi2c_imx->rate_per / ((1 << prescale) * lpi2c_imx->bitrate) > - 3 - (filt >> 1); > clkhi = (clk_cycle + I2C_CLK_RATIO) / (I2C_CLK_RATIO + 1); > clklo = clk_cycle - clkhi; > @@ -588,6 +603,18 @@ static int lpi2c_imx_probe(struct platform_device > *pdev) if (ret) > return ret; > > + lpi2c_imx->clk_change_nb.notifier_call = lpi2c_imx_clk_change_cb; > + ret = devm_clk_notifier_register(&pdev->dev, lpi2c_imx->clks[0].clk, > + &lpi2c_imx->clk_change_nb); > + if (ret) > + return dev_err_probe(&pdev->dev, ret, > + "can't register peripheral clock notifier\n"); > + lpi2c_imx->rate_per = clk_get_rate(lpi2c_imx->clks[0].clk); > + if (!lpi2c_imx->rate_per) { > + dev_err(&pdev->dev, "can't get I2C peripheral clock rate\n"); > + return -EINVAL; > + } > + > pm_runtime_set_autosuspend_delay(&pdev->dev, I2C_PM_TIMEOUT); > pm_runtime_use_autosuspend(&pdev->dev); > pm_runtime_get_noresume(&pdev->dev);
> > IIRC this is a general problem^w limitation of the clock framework, > > clock providers cannot use clocks themselves in certain callback, e.g. > > set_rate. > > Well, that's essentially impossible when this clock provider is attached via > i2c. i2c transfers potentially need to change or prepare clocks. So, as I get it, this is not a specific lpi2c problem but affecting any I2C controller driver which uses get_rate() to setup a transfer to a remote I2C clock provider? And this lockdep warning is a false-positive?
Hello Wolfgang, Am Sonntag, 30. April 2023, 09:05:55 CEST schrieb Wolfram Sang: > * PGP Signed by an unknown key > > > > IIRC this is a general problem^w limitation of the clock framework, > > > clock providers cannot use clocks themselves in certain callback, e.g. > > > set_rate. > > > > Well, that's essentially impossible when this clock provider is attached > > via i2c. i2c transfers potentially need to change or prepare clocks. > > So, as I get it, this is not a specific lpi2c problem but affecting any > I2C controller driver which uses get_rate() to setup a transfer to a > remote I2C clock provider? And this lockdep warning is a false-positive? Yes, IMHO this could potentially occur on every I2C controller driver, if a clock provider while holding the clk_prepare_lock, e.g. during registration, issues an i2c transfer. I'm not so sure if this is a false-positive, but more like trying to do a nested lock. Best regards Alexander
On 02.05.2023 08:50:06, Alexander Stein wrote: > Hello Wolfgang, > > Am Sonntag, 30. April 2023, 09:05:55 CEST schrieb Wolfram Sang: > > * PGP Signed by an unknown key > > > > > > IIRC this is a general problem^w limitation of the clock framework, > > > > clock providers cannot use clocks themselves in certain callback, e.g. > > > > set_rate. > > > > > > Well, that's essentially impossible when this clock provider is attached > > > via i2c. i2c transfers potentially need to change or prepare clocks. > > > > So, as I get it, this is not a specific lpi2c problem but affecting any > > I2C controller driver which uses get_rate() to setup a transfer to a > > remote I2C clock provider? And this lockdep warning is a false-positive? > > Yes, IMHO this could potentially occur on every I2C controller driver, if a > clock provider while holding the clk_prepare_lock, e.g. during registration, > issues an i2c transfer. > I'm not so sure if this is a false-positive, but more like trying to do a > nested lock. It's a general limitation of the clock framework. The clk_prepare_lock() is taken by clk_prepare() and by clk_get_rate(). So if you implement a clock provider driver that uses I2C, which might use clk_get_rate() it might deadlock. However there's a workaround for nested I2C calls: 533ddeb1e86f "(clk: allow reentrant calls into the clk framework, 2013-03-28)". This doesn't work for SPI, as it's using a worker thread. | https://elixir.bootlin.com/linux/v6.3/source/drivers/clk/clk.c#L128 regards, Marc
Hi, Am Freitag, 21. April 2023, 15:48:59 CEST schrieb Alexander Stein: > Hi, > > sorry for the delay. > > Am Freitag, 10. März 2023, 14:08:15 CEST schrieb A. Sverdlin: > > From: Alexander Sverdlin <alexander.sverdlin@siemens.com> > > > > One of the reasons to do it is to save some CPU cycles on cpu_freq_get() > > under mutex. The second reason if the (false-positive) lockdep splat > > caused > > by the recursive feature of the "prepare_lock" (one clock instance is I2C > > peripheral clock and another is pcf85063 RTC as clock provider): > > > > ====================================================== > > WARNING: possible circular locking dependency detected > > 5.15.71+... #1 Tainted: G O > > ------------------------------------------------------ > > fs-value/2332 is trying to acquire lock: > > ffff8000096cae08 (prepare_lock){+.+.}-{3:3}, at: clk_prepare_lock > > > > but task is already holding lock: > > ffff000011021100 (i2c_register_adapter){+.+.}-{3:3}, at: > > i2c_adapter_lock_bus > > > > which lock already depends on the new lock. > > > > the existing dependency chain (in reverse order) is: > > > > -> #2 (i2c_register_adapter){+.+.}-{3:3}: > > lock_acquire > > rt_mutex_lock_nested > > i2c_adapter_lock_bus > > i2c_transfer > > regmap_i2c_read > > _regmap_raw_read > > _regmap_bus_read > > _regmap_read > > regmap_read > > pcf85063_probe > > i2c_device_probe > > really_probe > > __driver_probe_device > > driver_probe_device > > __device_attach_driver > > bus_for_each_drv > > __device_attach > > device_initial_probe > > bus_probe_device > > device_add > > device_register > > i2c_new_client_device > > of_i2c_register_devices > > i2c_register_adapter > > __i2c_add_numbered_adapter > > i2c_add_adapter > > lpi2c_imx_probe > > platform_probe > > really_probe > > __driver_probe_device > > driver_probe_device > > __device_attach_driver > > bus_for_each_drv > > __device_attach > > device_initial_probe > > bus_probe_device > > deferred_probe_work_func > > process_one_work > > worker_thread > > kthread > > ret_from_fork > > > > -> #1 (rtc_pcf85063:560:(&config->regmap)->lock){+.+.}-{3:3}: > > lock_acquire > > __mutex_lock > > mutex_lock_nested > > regmap_lock_mutex > > regmap_read > > pcf85063_clkout_recalc_rate > > __clk_register > > devm_clk_register > > pcf85063_probe > > i2c_device_probe > > really_probe > > __driver_probe_device > > driver_probe_device > > __device_attach_driver > > bus_for_each_drv > > __device_attach > > device_initial_probe > > bus_probe_device > > device_add > > device_register > > i2c_new_client_device > > of_i2c_register_devices > > i2c_register_adapter > > __i2c_add_numbered_adapter > > i2c_add_adapter > > lpi2c_imx_probe > > platform_probe > > really_probe > > __driver_probe_device > > driver_probe_device > > __device_attach_driver > > bus_for_each_drv > > __device_attach > > device_initial_probe > > bus_probe_device > > deferred_probe_work_func > > process_one_work > > worker_thread > > kthread > > ret_from_fork > > > > -> #0 (prepare_lock){+.+.}-{3:3}: > > __lock_acquire > > lock_acquire.part.0 > > lock_acquire > > __mutex_lock > > mutex_lock_nested > > clk_prepare_lock > > clk_get_rate > > lpi2c_imx_xfer > > __i2c_transfer > > i2c_transfer > > regmap_i2c_read > > _regmap_raw_read > > regmap_raw_read > > regmap_bulk_read > > at24_read > > nvmem_reg_read > > bin_attr_nvmem_read > > sysfs_kf_bin_read > > kernfs_fop_read_iter > > new_sync_read > > vfs_read > > ksys_read > > __arm64_sys_read > > invoke_syscall > > ... > > > > other info that might help us debug this: > > > > Chain exists of: > > prepare_lock --> rtc_pcf85063:560:(&config->regmap)->lock --> > > > > i2c_register_adapter > > > > Possible unsafe locking scenario: > > CPU0 CPU1 > > ---- ---- > > > > lock(i2c_register_adapter); > > > > lock(rtc_pcf85063:560:(&config->regmap)->lock); > > lock(i2c_register_adapter); > > > > lock(prepare_lock); > > > > *** DEADLOCK *** > > > > 4 locks held by .../2332: > > #0: ffff0000146eb288 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_read_iter > > #1: ffff000010fe4400 (kn->active#72){.+.+}-{0:0}, at: > > kernfs_fop_read_iter > > #2: ffff0000110168e8 (&at24->lock){+.+.}-{3:3}, at: at24_read > > > > #3: ffff000011021100 (i2c_register_adapter){+.+.}-{3:3}, at: > > i2c_adapter_lock_bus > > > > stack backtrace: > > CPU: 1 PID: 2332 Comm: ... Tainted: G O 5.15.71+... #1 > > Hardware name: ... (DT) > > > > Call trace: > > dump_backtrace > > show_stack > > dump_stack_lvl > > dump_stack > > print_circular_bug > > check_noncircular > > __lock_acquire > > lock_acquire.part.0 > > lock_acquire > > __mutex_lock > > mutex_lock_nested > > clk_prepare_lock > > clk_get_rate > > lpi2c_imx_xfer > > __i2c_transfer > > i2c_transfer > > regmap_i2c_read > > _regmap_raw_read > > regmap_raw_read > > regmap_bulk_read > > at24_read > > nvmem_reg_read > > bin_attr_nvmem_read > > sysfs_kf_bin_read > > kernfs_fop_read_iter > > new_sync_read > > vfs_read > > ksys_read > > __arm64_sys_read > > invoke_syscall > > ... > > > > Fixes: a55fa9d0e42e ("i2c: imx-lpi2c: add low power i2c bus driver") > > Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com> > > --- > > > > drivers/i2c/busses/i2c-imx-lpi2c.c | 33 +++++++++++++++++++++++++++--- > > 1 file changed, 30 insertions(+), 3 deletions(-) > > > > Changelog: > > v3: fixed build error reported by kernel test robot <lkp@intel.com> > > > > https://lore.kernel.org/oe-kbuild-all/202303102010.pAv56wKs-lkp@intel.com/ > > v2: added clk_notifier as Alexander suggested > > > > diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c > > b/drivers/i2c/busses/i2c-imx-lpi2c.c index 188f2a36d2fd6..5f1d1d4e018bd > > 100644 > > --- a/drivers/i2c/busses/i2c-imx-lpi2c.c > > +++ b/drivers/i2c/busses/i2c-imx-lpi2c.c > > @@ -100,6 +100,8 @@ struct lpi2c_imx_struct { > > > > __u8 *rx_buf; > > __u8 *tx_buf; > > struct completion complete; > > > > + struct notifier_block clk_change_nb; > > + unsigned int rate_per; > > > > unsigned int msglen; > > unsigned int delivered; > > unsigned int block_data; > > > > @@ -198,24 +200,37 @@ static void lpi2c_imx_stop(struct lpi2c_imx_struct > > *lpi2c_imx) } while (1); > > > > } > > > > +static int lpi2c_imx_clk_change_cb(struct notifier_block *nb, > > + unsigned long action, void *data) > > +{ > > + struct clk_notifier_data *ndata = data; > > + struct lpi2c_imx_struct *lpi2c_imx = container_of(nb, > > + struct > > lpi2c_imx_struct, > > > + > > clk_change_nb); > > > + > > + if (action & POST_RATE_CHANGE) > > + lpi2c_imx->rate_per = ndata->new_rate; > > + > > + return NOTIFY_OK; > > +} > > + > > > > /* CLKLO = I2C_CLK_RATIO * CLKHI, SETHOLD = CLKHI, DATAVD = CLKHI/2 */ > > static int lpi2c_imx_config(struct lpi2c_imx_struct *lpi2c_imx) > > { > > > > u8 prescale, filt, sethold, clkhi, clklo, datavd; > > > > - unsigned int clk_rate, clk_cycle; > > + unsigned int clk_cycle; > > > > enum lpi2c_imx_pincfg pincfg; > > unsigned int temp; > > > > lpi2c_imx_set_mode(lpi2c_imx); > > > > - clk_rate = clk_get_rate(lpi2c_imx->clks[0].clk); > > > > if (lpi2c_imx->mode == HS || lpi2c_imx->mode == ULTRA_FAST) > > > > filt = 0; > > > > else > > > > filt = 2; > > > > for (prescale = 0; prescale <= 7; prescale++) { > > > > - clk_cycle = clk_rate / ((1 << prescale) * lpi2c_imx- > > > >bitrate) > > > > + clk_cycle = lpi2c_imx->rate_per / ((1 << prescale) * > > lpi2c_imx->bitrate) > > > - 3 - (filt >> 1); > > > > clkhi = (clk_cycle + I2C_CLK_RATIO) / (I2C_CLK_RATIO + 1); > > clklo = clk_cycle - clkhi; > > > > @@ -588,6 +603,18 @@ static int lpi2c_imx_probe(struct platform_device > > *pdev) if (ret) > > > > return ret; > > > > + lpi2c_imx->clk_change_nb.notifier_call = lpi2c_imx_clk_change_cb; > > + ret = devm_clk_notifier_register(&pdev->dev, lpi2c_imx->clks[0].clk, > > + &lpi2c_imx->clk_change_nb); > > + if (ret) > > + return dev_err_probe(&pdev->dev, ret, > > + "can't register peripheral clock > > notifier\n"); > > > + lpi2c_imx->rate_per = clk_get_rate(lpi2c_imx->clks[0].clk); > > + if (!lpi2c_imx->rate_per) { > > + dev_err(&pdev->dev, "can't get I2C peripheral clock > > rate\n"); > > > + return -EINVAL; > > + } > > + > > I would switch the order of the calls to devm_clk_notifier_register() and > clk_get_rate(). AFAICS this looks like a possible lost update. The notifier > might change rate_per before the (old) value from clk_get_rate is actually > assigned. > > With this change you fix the following call chain (from a kernel log) > > [ 4.562396] clk_prepare_lock+0x48/0x9c > [ 4.566740] clk_get_rate+0x1c/0x74 > [ 4.570736] lpi2c_imx_config+0x4c/0x190 > [ 4.575167] lpi2c_imx_master_enable+0x54/0x128 > [ 4.580205] lpi2c_imx_xfer+0x2c/0x3c8 > > Unfortuantely this was just hiding another call path from lpi2c_imx_xfer to > clk_bulk_prepare. Here is my kernel log: > > [ 22.264508] ====================================================== > [ 22.270697] WARNING: possible circular locking dependency detected > [ 22.276893] 6.3.0-rc7-next-20230420+ #6 Not tainted > [ 22.281782] ------------------------------------------------------ > [ 22.287968] kworker/2:3/93 is trying to acquire lock: > [ 22.293034] ffff800009d38bf8 (prepare_lock){+.+.}-{3:3}, at: > clk_prepare_lock+0x48/0x9c > [ 22.301095] > [ 22.301095] but task is already holding lock: > [ 22.306942] ffff0000039ab100 (i2c_register_adapter){+.+.}-{3:3}, at: > i2c_adapter_lock_bus+0x20/0x2c > [ 22.316046] > [ 22.316046] which lock already depends on the new lock. > [ 22.316046] > [ 22.324238] > [ 22.324238] the existing dependency chain (in reverse order) is: > [ 22.331727] > [ 22.331727] -> #2 (i2c_register_adapter){+.+.}-{3:3}: > [ 22.338295] __lock_acquire+0x370/0x6e8 > [ 22.342674] lock_acquire.part.0+0xcc/0x208 > [ 22.347399] lock_acquire+0x94/0x14c > [ 22.351509] rt_mutex_lock_nested+0x5c/0x98 > [ 22.356235] i2c_adapter_lock_bus+0x20/0x2c > [ 22.360961] i2c_transfer+0x80/0x114 > [ 22.365069] regmap_i2c_read+0x5c/0xa0 > [ 22.369362] _regmap_raw_read+0x110/0x2dc > [ 22.373905] _regmap_bus_read+0x40/0x74 > [ 22.378274] _regmap_read+0x74/0x248 > [ 22.382393] regmap_read+0x48/0x70 > [ 22.386337] pcf85063_probe+0xf0/0x4f4 > [ 22.390640] i2c_device_probe+0x100/0x2d4 > [ 22.395206] call_driver_probe+0x28/0x15c > [ 22.399750] really_probe+0x180/0x320 > [ 22.403946] __driver_probe_device+0x84/0x144 > [ 22.408837] driver_probe_device+0x38/0x150 > [ 22.413554] __device_attach_driver+0xcc/0x194 > [ 22.418532] bus_for_each_drv+0x80/0xdc > [ 22.422910] __device_attach+0xa8/0x1f8 > [ 22.426545] systemd-journald[128]: Oldest entry in /var/log/journal/ > e4579cc7db6747028247b9b859e132d6/system.joural is older than the configured > file retention duration (1month), suggesting rotation. > [ 22.427278] device_initial_probe+0x10/0x18 > [ 22.427290] bus_probe_device+0xa4/0xa8 > [ 22.427299] device_add+0x3b0/0x508 > [ 22.427311] device_register+0x1c/0x28 > [ 22.427323] i2c_new_client_device+0x1c8/0x2bc > [ 22.427333] of_i2c_register_device+0xb4/0xdc > [ 22.427344] of_i2c_register_devices+0x80/0x154 > [ 22.456329] systemd-journald[128]: /var/log/journal/ > e4579cc7db6747028247b9b859e132d6/system.journal: Journal heaer limits > reached or header out-of-date, rotating. > [ 22.458176] i2c_register_adapter+0x184/0x4c8 > [ 22.458202] __i2c_add_numbered_adapter+0x5c/0xa4 > [ 22.502097] i2c_add_adapter+0xa0/0xcc > [ 22.502122] lpi2c_imx_probe+0x23c/0x350 > [ 22.502135] platform_probe+0x64/0xfc > [ 22.502146] call_driver_probe+0x28/0x15c > [ 22.502155] really_probe+0x180/0x320 > [ 22.502164] __driver_probe_device+0x84/0x144 > [ 22.502173] driver_probe_device+0x38/0x150 > [ 22.502182] __device_attach_driver+0xcc/0x194 > [ 22.502191] bus_for_each_drv+0x80/0xdc > [ 22.502204] __device_attach+0xa8/0x1f8 > [ 22.502212] device_initial_probe+0x10/0x18 > [ 22.502222] bus_probe_device+0xa4/0xa8 > [ 22.502230] deferred_probe_work_func+0xa0/0xf0 > [ 22.502239] process_one_work+0x284/0x5b0 > [ 22.502252] worker_thread+0x68/0x39c > [ 22.502263] kthread+0x104/0x108 > [ 22.502274] ret_from_fork+0x10/0x20 > [ 22.502286] > [ 22.502286] -> #1 (rtc_pcf85063:594:(&config->regmap)->lock){+.+.}-{3:3}: > [ 22.502310] __lock_acquire+0x370/0x6e8 > [ 22.502322] lock_acquire.part.0+0xcc/0x208 > [ 22.502332] lock_acquire+0x94/0x14c > [ 22.502341] __mutex_lock+0x9c/0x838 > [ 22.502353] mutex_lock_nested+0x20/0x28 > [ 22.502364] regmap_lock_mutex+0x10/0x18 > [ 22.502377] regmap_read+0x38/0x70 > [ 22.502389] pcf85063_clkout_recalc_rate+0x2c/0x78 > [ 22.502403] __clk_core_init+0x46c/0x4e0 > [ 22.502417] __clk_register+0x160/0x23c > [ 22.502429] devm_clk_register+0x58/0xb4 > [ 22.502441] pcf85063_probe+0x238/0x4f4 > [ 22.502451] i2c_device_probe+0x100/0x2d4 > [ 22.502465] call_driver_probe+0x28/0x15c > [ 22.502473] really_probe+0x180/0x320 > [ 22.502482] __driver_probe_device+0x84/0x144 > [ 22.502491] driver_probe_device+0x38/0x150 > [ 22.502500] __device_attach_driver+0xcc/0x194 > [ 22.502509] bus_for_each_drv+0x80/0xdc > [ 22.502521] __device_attach+0xa8/0x1f8 > [ 22.502530] device_initial_probe+0x10/0x18 > [ 22.502539] bus_probe_device+0xa4/0xa8 > [ 22.502548] device_add+0x3b0/0x508 > [ 22.502559] device_register+0x1c/0x28 > [ 22.502570] i2c_new_client_device+0x1c8/0x2bc > [ 22.502580] of_i2c_register_device+0xb4/0xdc > [ OK ] Started Network Time Synchronization[ 22.502589] > of_i2c_register_devices+0x80/0x154 > .[ 22.502599] i2c_register_adapter+0x184/0x4c8 > > [ 22.502607] __i2c_add_numbered_adapter+0x5c/0xa4 > [ 22.502616] i2c_add_adapter+0xa0/0xcc > [ 22.502624] lpi2c_imx_probe+0x23c/0x350 > [ 22.502636] platform_probe+0x64/0xfc > [ 22.502646] call_driver_probe+0x28/0x15c > [ 22.502655] really_probe+0x180/0x320 > [ 22.502663] __driver_probe_device+0x84/0x144 > [ 22.502672] driver_probe_device+0x38/0x150 > [ 22.502681] __device_attach_driver+0xcc/0x194 > [ 22.502690] bus_for_each_drv+0x80/0xdc > [ 22.502702] __device_attach+0xa8/0x1f8 > [ 22.502711] device_initial_probe+0x10/0x18 > [ 22.502720] bus_probe_device+0xa4/0xa8 > [ 22.502729] deferred_probe_work_func+0xa0/0xf0 > [ 22.502738] process_one_work+0x284/0x5b0 > [ 22.502749] worker_thread+0x68/0x39c > [ 22.502760] kthread+0x104/0x108 > [ 22.502770] ret_from_fork+0x10/0x20 > [ 22.502779] > [ 22.502779] -> #0 (prepare_lock){+.+.}-{3:3}: > [ 22.502799] check_prev_add+0xb0/0xc80 > [ 22.502809] validate_chain+0x444/0x510 > [ 22.502818] __lock_acquire+0x370/0x6e8 > [ 22.502827] lock_acquire.part.0+0xcc/0x208 > [ 22.502837] lock_acquire+0x94/0x14c > [ 22.502846] __mutex_lock+0x9c/0x838 > [ 22.502857] mutex_lock_nested+0x20/0x28 > [ 22.502867] clk_prepare_lock+0x48/0x9c > [ 22.502878] clk_prepare+0x1c/0x3c > [ 22.502890] clk_bulk_prepare+0x48/0xcc > [ 22.502899] lpi2c_runtime_resume+0x30/0x84 > [ 22.502910] pm_generic_runtime_resume+0x28/0x3c > [ 22.502923] __genpd_runtime_resume+0x2c/0xa0 > [ 22.502935] genpd_runtime_resume+0xbc/0x308 > [ 22.502944] __rpm_callback+0x44/0x19c > [ 22.502953] rpm_callback+0x64/0x70 > [ 22.502962] rpm_resume+0x438/0x6d8 > [ 22.502970] __pm_runtime_resume+0x54/0xb0 > [ 22.502978] lpi2c_imx_master_enable+0x24/0x128 > [ 22.502989] lpi2c_imx_xfer+0x2c/0x3c8 > [ 22.502999] __i2c_transfer+0xe4/0x5a0 > [ 22.503008] i2c_transfer+0x90/0x114 > [ 22.503016] i2c_transfer_buffer_flags+0x58/0x84 > [ 22.503025] regmap_i2c_write+0x1c/0x4c > [ 22.503035] _regmap_raw_write_impl+0x7dc/0x944 > [ 22.503044] _regmap_bus_raw_write+0x5c/0x74 > [ 22.503052] _regmap_write+0x64/0x238 > [ 22.503060] _regmap_update_bits+0x100/0x11c > [ 22.503069] regmap_update_bits_base+0x60/0x90 > [ 22.503077] pca953x_gpio_set_value+0x74/0x90 > [ 22.503088] gpiod_set_raw_value_commit+0x6c/0x7c > [ 22.503098] gpiod_set_value_nocheck+0x68/0x70 > [ 22.503107] gpiod_set_value_cansleep+0x3c/0xa8 > [ 22.503116] gpio_led_set_blocking+0x54/0x7c > [ 22.503128] set_brightness_delayed+0x90/0xd8 > [ 22.503138] process_one_work+0x284/0x5b0 > [ 22.503149] worker_thread+0x68/0x39c > [ 22.503160] kthread+0x104/0x108 > [ 22.503169] ret_from_fork+0x10/0x20 > [ 22.503179] > [ 22.503179] other info that might help us debug this: > [ 22.503179] > [ 22.503183] Chain exists of: > [ 22.503183] prepare_lock --> rtc_pcf85063:594:(&config->regmap)->lock > --> i2c_register_adapter > [ 22.503183] > [ 22.503207] Possible unsafe locking scenario: > [ 22.503207] > [ 22.503210] CPU0 CPU1 > [ 22.503213] ---- ---- > [ 22.503216] lock(i2c_register_adapter); > [ 22.503225] > lock(rtc_pcf85063:594:(&config- > >regmap)->lock); > > [ 22.503235] lock(i2c_register_adapter); > [ 22.503244] lock(prepare_lock); > [ 22.503253] > [ 22.503253] *** DEADLOCK *** > > Now lpi2c_runtime_resume will call into clk_prepare() which also calls > clk_prepare_lock() (identical to clk_get_rate). > > Best regards, > Alexader > > > pm_runtime_set_autosuspend_delay(&pdev->dev, I2C_PM_TIMEOUT); > > pm_runtime_use_autosuspend(&pdev->dev); > > pm_runtime_get_noresume(&pdev->dev); With commit fa39065833db ("i2c: imx-lpi2c: avoid taking clk_prepare mutex in PM callbacks") in place, the additional deadlock warning regarding runtime resume is gone. So only the ordering issue needs to be addressed. Best regards, Alexander
Hello Alexander! On Mon, 2023-05-15 at 11:11 +0200, Alexander Stein wrote: > > [ 22.503179] other info that might help us debug this: > > [ 22.503179] > > [ 22.503183] Chain exists of: > > [ 22.503183] prepare_lock --> rtc_pcf85063:594:(&config- > > >regmap)->lock > > --> i2c_register_adapter > > [ 22.503183] > > [ 22.503207] Possible unsafe locking scenario: > > [ 22.503207] > > [ 22.503210] CPU0 CPU1 > > [ 22.503213] ---- ---- > > [ 22.503216] lock(i2c_register_adapter); > > [ 22.503225] > > lock(rtc_pcf85063:594:(&config- > > > regmap)->lock); > > > > [ 22.503235] > > lock(i2c_register_adapter); > > [ 22.503244] lock(prepare_lock); > > [ 22.503253] > > [ 22.503253] *** DEADLOCK *** > > > > Now lpi2c_runtime_resume will call into clk_prepare() which also > > calls > > clk_prepare_lock() (identical to clk_get_rate). > > > > Best regards, > > Alexader > > > > > pm_runtime_set_autosuspend_delay(&pdev->dev, > > > I2C_PM_TIMEOUT); > > > pm_runtime_use_autosuspend(&pdev->dev); > > > pm_runtime_get_noresume(&pdev->dev); > > With commit fa39065833db ("i2c: imx-lpi2c: avoid taking clk_prepare > mutex in > PM callbacks") in place, the additional deadlock warning regarding > runtime > resume is gone. > So only the ordering issue needs to be addressed. Unfortunately with both your (backported) and my patches applied I've got a 3rd warning: ====================================================== WARNING: possible circular locking dependency detected 5.15.71+git8e43aee #1 Tainted: G O ------------------------------------------------------ xxxxxxx/2238 is trying to acquire lock: ffff0000040bda40 (&desc->request_mutex){+.+.}-{3:3}, at: __setup_irq+0xbc/0x8bc but task is already holding lock: ffff000010ef1100 (i2c_register_adapter){+.+.}-{3:3}, at: i2c_adapter_lock_bus+0x2c/0x3c which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #5 (i2c_register_adapter){+.+.}-{3:3}: lock_acquire+0x68/0x84 rt_mutex_lock_nested+0x88/0xe0 i2c_adapter_lock_bus+0x2c/0x3c i2c_transfer+0x58/0x130 regmap_i2c_read+0x64/0xb0 _regmap_raw_read+0x114/0x440 _regmap_bus_read+0x4c/0x84 _regmap_read+0x6c/0x270 regmap_read+0x54/0x80 pcf85063_probe+0xec/0x4cc i2c_device_probe+0x10c/0x350 really_probe+0xc4/0x470 __driver_probe_device+0x11c/0x190 driver_probe_device+0x48/0x110 __device_attach_driver+0xc4/0x160 bus_for_each_drv+0x80/0xe0 __device_attach+0xb0/0x1f0 device_initial_probe+0x1c/0x2c bus_probe_device+0xa4/0xb0 device_add+0x398/0x8ac device_register+0x28/0x40 i2c_new_client_device+0x144/0x290 of_i2c_register_devices+0x18c/0x230 i2c_register_adapter+0x1dc/0x6b0 __i2c_add_numbered_adapter+0x68/0xbc i2c_add_adapter+0xb0/0xe0 lpi2c_imx_probe+0x3a4/0x670 platform_probe+0x70/0xec really_probe+0xc4/0x470 __driver_probe_device+0x11c/0x190 driver_probe_device+0x48/0x110 __device_attach_driver+0xc4/0x160 bus_for_each_drv+0x80/0xe0 __device_attach+0xb0/0x1f0 device_initial_probe+0x1c/0x2c bus_probe_device+0xa4/0xb0 deferred_probe_work_func+0xb8/0x110 process_one_work+0x27c/0x6c4 worker_thread+0x7c/0x450 kthread+0x168/0x17c ret_from_fork+0x10/0x20 -> #4 (rtc_pcf85063:560:(&config->regmap)->lock){+.+.}-{3:3}: lock_acquire+0x68/0x84 __mutex_lock+0xa8/0x4d0 mutex_lock_nested+0x48/0x54 regmap_lock_mutex+0x1c/0x30 regmap_read+0x44/0x80 pcf85063_clkout_recalc_rate+0x34/0x80 __clk_register+0x520/0x880 devm_clk_register+0x64/0xc4 pcf85063_probe+0x24c/0x4cc i2c_device_probe+0x10c/0x350 really_probe+0xc4/0x470 __driver_probe_device+0x11c/0x190 driver_probe_device+0x48/0x110 __device_attach_driver+0xc4/0x160 bus_for_each_drv+0x80/0xe0 __device_attach+0xb0/0x1f0 device_initial_probe+0x1c/0x2c bus_probe_device+0xa4/0xb0 device_add+0x398/0x8ac device_register+0x28/0x40 i2c_new_client_device+0x144/0x290 of_i2c_register_devices+0x18c/0x230 i2c_register_adapter+0x1dc/0x6b0 __i2c_add_numbered_adapter+0x68/0xbc i2c_add_adapter+0xb0/0xe0 lpi2c_imx_probe+0x3a4/0x670 platform_probe+0x70/0xec really_probe+0xc4/0x470 __driver_probe_device+0x11c/0x190 driver_probe_device+0x48/0x110 __device_attach_driver+0xc4/0x160 bus_for_each_drv+0x80/0xe0 __device_attach+0xb0/0x1f0 device_initial_probe+0x1c/0x2c bus_probe_device+0xa4/0xb0 deferred_probe_work_func+0xb8/0x110 process_one_work+0x27c/0x6c4 worker_thread+0x7c/0x450 kthread+0x168/0x17c ret_from_fork+0x10/0x20 -> #3 (prepare_lock){+.+.}-{3:3}: lock_acquire+0x68/0x84 __mutex_lock+0xa8/0x4d0 mutex_lock_nested+0x48/0x54 clk_prepare_lock+0x50/0xb0 clk_prepare+0x28/0x50 fec_runtime_resume+0x3c/0xe0 pm_generic_runtime_resume+0x34/0x50 __genpd_runtime_resume+0x38/0x90 genpd_runtime_resume+0xa0/0x304 __rpm_callback+0x50/0x1b0 rpm_callback+0x40/0x80 rpm_resume+0x448/0x6e0 __pm_runtime_resume+0x50/0xc0 fec_enet_mdio_read+0x48/0x190 __mdiobus_read+0x48/0xb0 mdiobus_read_nested+0x48/0x70 mv88e6xxx_smi_dual_direct_read+0x2c/0x50 mv88e6xxx_read+0x64/0xf0 mv88e6xxx_g1_read+0x28/0x34 mv88e6xxx_g1_irq_thread_work+0x50/0x17c mv88e6xxx_irq_poll+0x28/0x50 kthread_worker_fn+0x100/0x480 kthread+0x168/0x17c ret_from_fork+0x10/0x20 -> #2 (&bus->mdio_lock/2){+.+.}-{3:3}: lock_acquire+0x68/0x84 __mutex_lock+0xa8/0x4d0 mutex_lock_nested+0x48/0x54 mdiobus_read_nested+0x38/0x70 mv88e6xxx_smi_dual_direct_read+0x2c/0x50 mv88e6xxx_read+0x64/0xf0 mv88e6xxx_port_read+0x24/0x30 mv88e6xxx_probe+0x250/0x7f0 mdio_probe+0x3c/0x80 really_probe+0xc4/0x470 __driver_probe_device+0x11c/0x190 driver_probe_device+0x48/0x110 __device_attach_driver+0xc4/0x160 bus_for_each_drv+0x80/0xe0 __device_attach+0xb0/0x1f0 device_initial_probe+0x1c/0x2c bus_probe_device+0xa4/0xb0 deferred_probe_work_func+0xb8/0x110 process_one_work+0x27c/0x6c4 worker_thread+0x7c/0x450 kthread+0x168/0x17c ret_from_fork+0x10/0x20 -> #1 (&chip->reg_lock){+.+.}-{3:3}: lock_acquire+0x68/0x84 __mutex_lock+0xa8/0x4d0 mutex_lock_nested+0x48/0x54 mv88e6xxx_g1_irq_bus_lock+0x24/0x30 __setup_irq+0x6e0/0x8bc request_threaded_irq+0xf4/0x1b4 mv88e6xxx_g2_irq_setup+0x1f0/0x2b4 mv88e6xxx_probe+0x480/0x7f0 mdio_probe+0x3c/0x80 really_probe+0xc4/0x470 __driver_probe_device+0x11c/0x190 driver_probe_device+0x48/0x110 __device_attach_driver+0xc4/0x160 bus_for_each_drv+0x80/0xe0 __device_attach+0xb0/0x1f0 device_initial_probe+0x1c/0x2c bus_probe_device+0xa4/0xb0 deferred_probe_work_func+0xb8/0x110 process_one_work+0x27c/0x6c4 worker_thread+0x7c/0x450 kthread+0x168/0x17c ret_from_fork+0x10/0x20 -> #0 (&desc->request_mutex){+.+.}-{3:3}: __lock_acquire+0x12a4/0x20a0 lock_acquire.part.0+0xe0/0x230 lock_acquire+0x68/0x84 __mutex_lock+0xa8/0x4d0 mutex_lock_nested+0x48/0x54 __setup_irq+0xbc/0x8bc request_threaded_irq+0xf4/0x1b4 devm_request_threaded_irq+0x88/0x104 lpi2c_runtime_resume+0x70/0xe4 pm_generic_runtime_resume+0x34/0x50 __genpd_runtime_resume+0x38/0x90 genpd_runtime_resume+0xa0/0x304 __rpm_callback+0x50/0x1b0 rpm_callback+0x74/0x80 rpm_resume+0x448/0x6e0 __pm_runtime_resume+0x50/0xc0 lpi2c_imx_xfer+0x60/0xa5c __i2c_transfer+0x174/0xa80 i2c_transfer+0x68/0x130 regmap_i2c_read+0x64/0xb0 _regmap_raw_read+0x114/0x440 regmap_raw_read+0x19c/0x28c regmap_bulk_read+0x1b8/0x244 at24_read+0x14c/0x2c4 nvmem_reg_read+0x2c/0x54 bin_attr_nvmem_read+0x8c/0xbc sysfs_kf_bin_read+0x74/0x94 kernfs_fop_read_iter+0xb0/0x1d0 new_sync_read+0xf0/0x184 vfs_read+0x154/0x1f0 ksys_read+0x70/0x100 __arm64_sys_read+0x24/0x30 invoke_syscall+0x50/0x120 el0_svc_common.constprop.0+0x68/0x124 do_el0_svc+0x30/0x9c el0_svc+0x54/0x110 el0t_64_sync_handler+0xa4/0x130 el0t_64_sync+0x1a0/0x1a4 other info that might help us debug this: Chain exists of: &desc->request_mutex --> rtc_pcf85063:560:(&config->regmap)->lock --> i2c_register_adapter Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(i2c_register_adapter); lock(rtc_pcf85063:560:(&config->regmap)- >lock); lock(i2c_register_adapter); lock(&desc->request_mutex); *** DEADLOCK *** 4 locks held by xxxxxxx/2238: #0: ffff000015a64488 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_read_iter+0x74/0x1d0 #1: ffff0000119e2400 (kn->active#58){.+.+}-{0:0}, at: kernfs_fop_read_iter+0x7c/0x1d0 #2: ffff0000119a26e8 (&at24->lock){+.+.}-{3:3}, at: at24_read+0x8c/0x2c4 #3: ffff000010ef1100 (i2c_register_adapter){+.+.}-{3:3}, at: i2c_adapter_lock_bus+0x2c/0x3c stack backtrace: CPU: 1 PID: 2238 Comm: xxxxxxx Tainted: G O 5.15.71+git8e43aee #1 Hardware name: Siemens PXC5.E24 (DT) Call trace: dump_backtrace+0x0/0x1d4 show_stack+0x20/0x2c dump_stack_lvl+0x8c/0xb8 dump_stack+0x18/0x34 print_circular_bug+0x1f8/0x200 check_noncircular+0x130/0x144 __lock_acquire+0x12a4/0x20a0 lock_acquire.part.0+0xe0/0x230 lock_acquire+0x68/0x84 __mutex_lock+0xa8/0x4d0 mutex_lock_nested+0x48/0x54 __setup_irq+0xbc/0x8bc request_threaded_irq+0xf4/0x1b4 devm_request_threaded_irq+0x88/0x104 lpi2c_runtime_resume+0x70/0xe4 pm_generic_runtime_resume+0x34/0x50 __genpd_runtime_resume+0x38/0x90 genpd_runtime_resume+0xa0/0x304 __rpm_callback+0x50/0x1b0 rpm_callback+0x74/0x80 rpm_resume+0x448/0x6e0 __pm_runtime_resume+0x50/0xc0 lpi2c_imx_xfer+0x60/0xa5c __i2c_transfer+0x174/0xa80 i2c_transfer+0x68/0x130 regmap_i2c_read+0x64/0xb0 _regmap_raw_read+0x114/0x440 regmap_raw_read+0x19c/0x28c regmap_bulk_read+0x1b8/0x244 at24_read+0x14c/0x2c4 nvmem_reg_read+0x2c/0x54 bin_attr_nvmem_read+0x8c/0xbc sysfs_kf_bin_read+0x74/0x94 kernfs_fop_read_iter+0xb0/0x1d0 new_sync_read+0xf0/0x184 vfs_read+0x154/0x1f0 ksys_read+0x70/0x100 __arm64_sys_read+0x24/0x30 invoke_syscall+0x50/0x120 el0_svc_common.constprop.0+0x68/0x124 do_el0_svc+0x30/0x9c el0_svc+0x54/0x110 el0t_64_sync_handler+0xa4/0x130 el0t_64_sync+0x1a0/0x1a4 So this doesn't look like an end of the story yet, unfortunately.
Hi Alexander, Am Montag, 15. Mai 2023, 14:04:10 CEST schrieb Sverdlin, Alexander: > Hello Alexander! > > On Mon, 2023-05-15 at 11:11 +0200, Alexander Stein wrote: > > > > [ 22.503179] other info that might help us debug this: > > > [ 22.503179] > > > [ 22.503183] Chain exists of: > > > [ 22.503183] prepare_lock --> rtc_pcf85063:594:(&config- > > > > > > >regmap)->lock > > > > > > --> i2c_register_adapter > > > [ 22.503183] > > > [ 22.503207] Possible unsafe locking scenario: > > > [ 22.503207] > > > [ 22.503210] CPU0 CPU1 > > > [ 22.503213] ---- ---- > > > [ 22.503216] lock(i2c_register_adapter); > > > [ 22.503225] > > > lock(rtc_pcf85063:594:(&config- > > > > > > > regmap)->lock); > > > > > > > > > [ 22.503235] > > > lock(i2c_register_adapter); > > > [ 22.503244] lock(prepare_lock); > > > [ 22.503253] > > > [ 22.503253] *** DEADLOCK *** > > > > > > Now lpi2c_runtime_resume will call into clk_prepare() which also > > > calls > > > clk_prepare_lock() (identical to clk_get_rate). > > > > > > Best regards, > > > Alexader > > > > > > > > > > pm_runtime_set_autosuspend_delay(&pdev->dev, > > > > I2C_PM_TIMEOUT); > > > > pm_runtime_use_autosuspend(&pdev->dev); > > > > pm_runtime_get_noresume(&pdev->dev); > > > > > > With commit fa39065833db ("i2c: imx-lpi2c: avoid taking clk_prepare > > mutex in > > PM callbacks") in place, the additional deadlock warning regarding > > runtime > > resume is gone. > > So only the ordering issue needs to be addressed. > > > Unfortunately with both your (backported) and my patches applied I've > got a 3rd warning: > > ====================================================== > WARNING: possible circular locking dependency detected > 5.15.71+git8e43aee #1 Tainted: G O > ------------------------------------------------------ > xxxxxxx/2238 is trying to acquire lock: > ffff0000040bda40 (&desc->request_mutex){+.+.}-{3:3}, at: > __setup_irq+0xbc/0x8bc > > but task is already holding lock: > ffff000010ef1100 (i2c_register_adapter){+.+.}-{3:3}, at: > i2c_adapter_lock_bus+0x2c/0x3c > > which lock already depends on the new lock. > > > the existing dependency chain (in reverse order) is: > > -> #5 (i2c_register_adapter){+.+.}-{3:3}: > lock_acquire+0x68/0x84 > rt_mutex_lock_nested+0x88/0xe0 > i2c_adapter_lock_bus+0x2c/0x3c > i2c_transfer+0x58/0x130 > regmap_i2c_read+0x64/0xb0 > _regmap_raw_read+0x114/0x440 > _regmap_bus_read+0x4c/0x84 > _regmap_read+0x6c/0x270 > regmap_read+0x54/0x80 > pcf85063_probe+0xec/0x4cc > i2c_device_probe+0x10c/0x350 > really_probe+0xc4/0x470 > __driver_probe_device+0x11c/0x190 > driver_probe_device+0x48/0x110 > __device_attach_driver+0xc4/0x160 > bus_for_each_drv+0x80/0xe0 > __device_attach+0xb0/0x1f0 > device_initial_probe+0x1c/0x2c > bus_probe_device+0xa4/0xb0 > device_add+0x398/0x8ac > device_register+0x28/0x40 > i2c_new_client_device+0x144/0x290 > of_i2c_register_devices+0x18c/0x230 > i2c_register_adapter+0x1dc/0x6b0 > __i2c_add_numbered_adapter+0x68/0xbc > i2c_add_adapter+0xb0/0xe0 > lpi2c_imx_probe+0x3a4/0x670 > platform_probe+0x70/0xec > really_probe+0xc4/0x470 > __driver_probe_device+0x11c/0x190 > driver_probe_device+0x48/0x110 > __device_attach_driver+0xc4/0x160 > bus_for_each_drv+0x80/0xe0 > __device_attach+0xb0/0x1f0 > device_initial_probe+0x1c/0x2c > bus_probe_device+0xa4/0xb0 > deferred_probe_work_func+0xb8/0x110 > process_one_work+0x27c/0x6c4 > worker_thread+0x7c/0x450 > kthread+0x168/0x17c > ret_from_fork+0x10/0x20 > > -> #4 (rtc_pcf85063:560:(&config->regmap)->lock){+.+.}-{3:3}: > lock_acquire+0x68/0x84 > __mutex_lock+0xa8/0x4d0 > mutex_lock_nested+0x48/0x54 > regmap_lock_mutex+0x1c/0x30 > regmap_read+0x44/0x80 > pcf85063_clkout_recalc_rate+0x34/0x80 > __clk_register+0x520/0x880 > devm_clk_register+0x64/0xc4 > pcf85063_probe+0x24c/0x4cc > i2c_device_probe+0x10c/0x350 > really_probe+0xc4/0x470 > __driver_probe_device+0x11c/0x190 > driver_probe_device+0x48/0x110 > __device_attach_driver+0xc4/0x160 > bus_for_each_drv+0x80/0xe0 > __device_attach+0xb0/0x1f0 > device_initial_probe+0x1c/0x2c > bus_probe_device+0xa4/0xb0 > device_add+0x398/0x8ac > device_register+0x28/0x40 > i2c_new_client_device+0x144/0x290 > of_i2c_register_devices+0x18c/0x230 > i2c_register_adapter+0x1dc/0x6b0 > __i2c_add_numbered_adapter+0x68/0xbc > i2c_add_adapter+0xb0/0xe0 > lpi2c_imx_probe+0x3a4/0x670 > platform_probe+0x70/0xec > really_probe+0xc4/0x470 > __driver_probe_device+0x11c/0x190 > driver_probe_device+0x48/0x110 > __device_attach_driver+0xc4/0x160 > bus_for_each_drv+0x80/0xe0 > __device_attach+0xb0/0x1f0 > device_initial_probe+0x1c/0x2c > bus_probe_device+0xa4/0xb0 > deferred_probe_work_func+0xb8/0x110 > process_one_work+0x27c/0x6c4 > worker_thread+0x7c/0x450 > kthread+0x168/0x17c > ret_from_fork+0x10/0x20 > > -> #3 (prepare_lock){+.+.}-{3:3}: > lock_acquire+0x68/0x84 > __mutex_lock+0xa8/0x4d0 > mutex_lock_nested+0x48/0x54 > clk_prepare_lock+0x50/0xb0 > clk_prepare+0x28/0x50 > fec_runtime_resume+0x3c/0xe0 > pm_generic_runtime_resume+0x34/0x50 > __genpd_runtime_resume+0x38/0x90 > genpd_runtime_resume+0xa0/0x304 > __rpm_callback+0x50/0x1b0 > rpm_callback+0x40/0x80 > rpm_resume+0x448/0x6e0 > __pm_runtime_resume+0x50/0xc0 > fec_enet_mdio_read+0x48/0x190 > __mdiobus_read+0x48/0xb0 > mdiobus_read_nested+0x48/0x70 > mv88e6xxx_smi_dual_direct_read+0x2c/0x50 > mv88e6xxx_read+0x64/0xf0 > mv88e6xxx_g1_read+0x28/0x34 > mv88e6xxx_g1_irq_thread_work+0x50/0x17c > mv88e6xxx_irq_poll+0x28/0x50 > kthread_worker_fn+0x100/0x480 > kthread+0x168/0x17c > ret_from_fork+0x10/0x20 > > -> #2 (&bus->mdio_lock/2){+.+.}-{3:3}: > lock_acquire+0x68/0x84 > __mutex_lock+0xa8/0x4d0 > mutex_lock_nested+0x48/0x54 > mdiobus_read_nested+0x38/0x70 > mv88e6xxx_smi_dual_direct_read+0x2c/0x50 > mv88e6xxx_read+0x64/0xf0 > mv88e6xxx_port_read+0x24/0x30 > mv88e6xxx_probe+0x250/0x7f0 > mdio_probe+0x3c/0x80 > really_probe+0xc4/0x470 > __driver_probe_device+0x11c/0x190 > driver_probe_device+0x48/0x110 > __device_attach_driver+0xc4/0x160 > bus_for_each_drv+0x80/0xe0 > __device_attach+0xb0/0x1f0 > device_initial_probe+0x1c/0x2c > bus_probe_device+0xa4/0xb0 > deferred_probe_work_func+0xb8/0x110 > process_one_work+0x27c/0x6c4 > worker_thread+0x7c/0x450 > kthread+0x168/0x17c > ret_from_fork+0x10/0x20 > > -> #1 (&chip->reg_lock){+.+.}-{3:3}: > lock_acquire+0x68/0x84 > __mutex_lock+0xa8/0x4d0 > mutex_lock_nested+0x48/0x54 > mv88e6xxx_g1_irq_bus_lock+0x24/0x30 > __setup_irq+0x6e0/0x8bc > request_threaded_irq+0xf4/0x1b4 > mv88e6xxx_g2_irq_setup+0x1f0/0x2b4 > mv88e6xxx_probe+0x480/0x7f0 > mdio_probe+0x3c/0x80 > really_probe+0xc4/0x470 > __driver_probe_device+0x11c/0x190 > driver_probe_device+0x48/0x110 > __device_attach_driver+0xc4/0x160 > bus_for_each_drv+0x80/0xe0 > __device_attach+0xb0/0x1f0 > device_initial_probe+0x1c/0x2c > bus_probe_device+0xa4/0xb0 > deferred_probe_work_func+0xb8/0x110 > process_one_work+0x27c/0x6c4 > worker_thread+0x7c/0x450 > kthread+0x168/0x17c > ret_from_fork+0x10/0x20 > > -> #0 (&desc->request_mutex){+.+.}-{3:3}: > __lock_acquire+0x12a4/0x20a0 > lock_acquire.part.0+0xe0/0x230 > lock_acquire+0x68/0x84 > __mutex_lock+0xa8/0x4d0 > mutex_lock_nested+0x48/0x54 > __setup_irq+0xbc/0x8bc > request_threaded_irq+0xf4/0x1b4 > devm_request_threaded_irq+0x88/0x104 > lpi2c_runtime_resume+0x70/0xe4 This looks like the NXP downstream kernel, requesting the IRQ from within runtime resume. > pm_generic_runtime_resume+0x34/0x50 > __genpd_runtime_resume+0x38/0x90 > genpd_runtime_resume+0xa0/0x304 > __rpm_callback+0x50/0x1b0 > rpm_callback+0x74/0x80 > rpm_resume+0x448/0x6e0 > __pm_runtime_resume+0x50/0xc0 > lpi2c_imx_xfer+0x60/0xa5c > __i2c_transfer+0x174/0xa80 > i2c_transfer+0x68/0x130 > regmap_i2c_read+0x64/0xb0 > _regmap_raw_read+0x114/0x440 > regmap_raw_read+0x19c/0x28c > regmap_bulk_read+0x1b8/0x244 > at24_read+0x14c/0x2c4 > nvmem_reg_read+0x2c/0x54 > bin_attr_nvmem_read+0x8c/0xbc > sysfs_kf_bin_read+0x74/0x94 > kernfs_fop_read_iter+0xb0/0x1d0 > new_sync_read+0xf0/0x184 > vfs_read+0x154/0x1f0 > ksys_read+0x70/0x100 > __arm64_sys_read+0x24/0x30 > invoke_syscall+0x50/0x120 > el0_svc_common.constprop.0+0x68/0x124 > do_el0_svc+0x30/0x9c > el0_svc+0x54/0x110 > el0t_64_sync_handler+0xa4/0x130 > el0t_64_sync+0x1a0/0x1a4 > > other info that might help us debug this: > > Chain exists of: > &desc->request_mutex --> rtc_pcf85063:560:(&config->regmap)->lock --> > i2c_register_adapter > > Possible unsafe locking scenario: > > CPU0 CPU1 > ---- ---- > lock(i2c_register_adapter); > lock(rtc_pcf85063:560:(&config->regmap)- > > >lock); > > lock(i2c_register_adapter); > lock(&desc->request_mutex); > > *** DEADLOCK *** > > 4 locks held by xxxxxxx/2238: > #0: ffff000015a64488 (&of->mutex){+.+.}-{3:3}, at: > kernfs_fop_read_iter+0x74/0x1d0 > #1: ffff0000119e2400 (kn->active#58){.+.+}-{0:0}, at: > kernfs_fop_read_iter+0x7c/0x1d0 > #2: ffff0000119a26e8 (&at24->lock){+.+.}-{3:3}, at: > at24_read+0x8c/0x2c4 > #3: ffff000010ef1100 (i2c_register_adapter){+.+.}-{3:3}, at: > i2c_adapter_lock_bus+0x2c/0x3c > > stack backtrace: > CPU: 1 PID: 2238 Comm: xxxxxxx Tainted: G O > 5.15.71+git8e43aee #1 > Hardware name: Siemens PXC5.E24 (DT) > Call trace: > dump_backtrace+0x0/0x1d4 > show_stack+0x20/0x2c > dump_stack_lvl+0x8c/0xb8 > dump_stack+0x18/0x34 > print_circular_bug+0x1f8/0x200 > check_noncircular+0x130/0x144 > __lock_acquire+0x12a4/0x20a0 > lock_acquire.part.0+0xe0/0x230 > lock_acquire+0x68/0x84 > __mutex_lock+0xa8/0x4d0 > mutex_lock_nested+0x48/0x54 > __setup_irq+0xbc/0x8bc > request_threaded_irq+0xf4/0x1b4 > devm_request_threaded_irq+0x88/0x104 > lpi2c_runtime_resume+0x70/0xe4 It seems your (possible) deadlock is triggered along devm_request_irq() during resume. As mainline just enables the clocks, there is nothing we can do here. Your patch still is sensible, can you send a new version with the review addressed? Thanks. Best regards, Alexander > pm_generic_runtime_resume+0x34/0x50 > __genpd_runtime_resume+0x38/0x90 > genpd_runtime_resume+0xa0/0x304 > __rpm_callback+0x50/0x1b0 > rpm_callback+0x74/0x80 > rpm_resume+0x448/0x6e0 > __pm_runtime_resume+0x50/0xc0 > lpi2c_imx_xfer+0x60/0xa5c > __i2c_transfer+0x174/0xa80 > i2c_transfer+0x68/0x130 > regmap_i2c_read+0x64/0xb0 > _regmap_raw_read+0x114/0x440 > regmap_raw_read+0x19c/0x28c > regmap_bulk_read+0x1b8/0x244 > at24_read+0x14c/0x2c4 > nvmem_reg_read+0x2c/0x54 > bin_attr_nvmem_read+0x8c/0xbc > sysfs_kf_bin_read+0x74/0x94 > kernfs_fop_read_iter+0xb0/0x1d0 > new_sync_read+0xf0/0x184 > vfs_read+0x154/0x1f0 > ksys_read+0x70/0x100 > __arm64_sys_read+0x24/0x30 > invoke_syscall+0x50/0x120 > el0_svc_common.constprop.0+0x68/0x124 > do_el0_svc+0x30/0x9c > el0_svc+0x54/0x110 > el0t_64_sync_handler+0xa4/0x130 > el0t_64_sync+0x1a0/0x1a4 > > So this doesn't look like an end of the story yet, unfortunately. > > -- > Alexander Sverdlin > Siemens AG > www.siemens.com
Hello Alexander! On Mon, 2023-05-15 at 14:32 +0200, Alexander Stein wrote: > > stack backtrace: > > CPU: 1 PID: 2238 Comm: xxxxxxx Tainted: G O > > 5.15.71+git8e43aee #1 > > Hardware name: Siemens PXC5.E24 (DT) > > Call trace: > > dump_backtrace+0x0/0x1d4 > > show_stack+0x20/0x2c > > dump_stack_lvl+0x8c/0xb8 > > dump_stack+0x18/0x34 > > print_circular_bug+0x1f8/0x200 > > check_noncircular+0x130/0x144 > > __lock_acquire+0x12a4/0x20a0 > > lock_acquire.part.0+0xe0/0x230 > > lock_acquire+0x68/0x84 > > __mutex_lock+0xa8/0x4d0 > > mutex_lock_nested+0x48/0x54 > > __setup_irq+0xbc/0x8bc > > request_threaded_irq+0xf4/0x1b4 > > devm_request_threaded_irq+0x88/0x104 > > lpi2c_runtime_resume+0x70/0xe4 > > It seems your (possible) deadlock is triggered along > devm_request_irq() during > resume. You are right! Thank you for looking into this! > As mainline just enables the clocks, there is nothing we can do here. > Your > patch still is sensible, can you send a new version with the review > addressed? Sure, I'll do!
Hello Alexander, On Fri, 2023-04-21 at 15:48 +0200, Alexander Stein wrote: > > + lpi2c_imx->clk_change_nb.notifier_call = > > lpi2c_imx_clk_change_cb; > > + ret = devm_clk_notifier_register(&pdev->dev, lpi2c_imx- > > >clks[0].clk, > > + &lpi2c_imx- > > >clk_change_nb); > > + if (ret) > > + return dev_err_probe(&pdev->dev, ret, > > + "can't register peripheral > > clock > notifier\n"); > > + lpi2c_imx->rate_per = clk_get_rate(lpi2c_imx->clks[0].clk); > > + if (!lpi2c_imx->rate_per) { > > + dev_err(&pdev->dev, "can't get I2C peripheral clock > rate\n"); > > + return -EINVAL; > > + } > > + > > I would switch the order of the calls to devm_clk_notifier_register() > and > clk_get_rate(). AFAICS this looks like a possible lost update. The > notifier > might change rate_per before the (old) value from clk_get_rate is > actually > assigned. just swapping would not be enough I believe, in the case update event happens between clk_get_rate() and devm_clk_notifier_register(). I'll think about it...
diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c b/drivers/i2c/busses/i2c-imx-lpi2c.c index 188f2a36d2fd6..5f1d1d4e018bd 100644 --- a/drivers/i2c/busses/i2c-imx-lpi2c.c +++ b/drivers/i2c/busses/i2c-imx-lpi2c.c @@ -100,6 +100,8 @@ struct lpi2c_imx_struct { __u8 *rx_buf; __u8 *tx_buf; struct completion complete; + struct notifier_block clk_change_nb; + unsigned int rate_per; unsigned int msglen; unsigned int delivered; unsigned int block_data; @@ -198,24 +200,37 @@ static void lpi2c_imx_stop(struct lpi2c_imx_struct *lpi2c_imx) } while (1); } +static int lpi2c_imx_clk_change_cb(struct notifier_block *nb, + unsigned long action, void *data) +{ + struct clk_notifier_data *ndata = data; + struct lpi2c_imx_struct *lpi2c_imx = container_of(nb, + struct lpi2c_imx_struct, + clk_change_nb); + + if (action & POST_RATE_CHANGE) + lpi2c_imx->rate_per = ndata->new_rate; + + return NOTIFY_OK; +} + /* CLKLO = I2C_CLK_RATIO * CLKHI, SETHOLD = CLKHI, DATAVD = CLKHI/2 */ static int lpi2c_imx_config(struct lpi2c_imx_struct *lpi2c_imx) { u8 prescale, filt, sethold, clkhi, clklo, datavd; - unsigned int clk_rate, clk_cycle; + unsigned int clk_cycle; enum lpi2c_imx_pincfg pincfg; unsigned int temp; lpi2c_imx_set_mode(lpi2c_imx); - clk_rate = clk_get_rate(lpi2c_imx->clks[0].clk); if (lpi2c_imx->mode == HS || lpi2c_imx->mode == ULTRA_FAST) filt = 0; else filt = 2; for (prescale = 0; prescale <= 7; prescale++) { - clk_cycle = clk_rate / ((1 << prescale) * lpi2c_imx->bitrate) + clk_cycle = lpi2c_imx->rate_per / ((1 << prescale) * lpi2c_imx->bitrate) - 3 - (filt >> 1); clkhi = (clk_cycle + I2C_CLK_RATIO) / (I2C_CLK_RATIO + 1); clklo = clk_cycle - clkhi; @@ -588,6 +603,18 @@ static int lpi2c_imx_probe(struct platform_device *pdev) if (ret) return ret; + lpi2c_imx->clk_change_nb.notifier_call = lpi2c_imx_clk_change_cb; + ret = devm_clk_notifier_register(&pdev->dev, lpi2c_imx->clks[0].clk, + &lpi2c_imx->clk_change_nb); + if (ret) + return dev_err_probe(&pdev->dev, ret, + "can't register peripheral clock notifier\n"); + lpi2c_imx->rate_per = clk_get_rate(lpi2c_imx->clks[0].clk); + if (!lpi2c_imx->rate_per) { + dev_err(&pdev->dev, "can't get I2C peripheral clock rate\n"); + return -EINVAL; + } + pm_runtime_set_autosuspend_delay(&pdev->dev, I2C_PM_TIMEOUT); pm_runtime_use_autosuspend(&pdev->dev); pm_runtime_get_noresume(&pdev->dev);