| Message ID | 20180813211614.16440-4-contact@stefanchrist.eu (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | I2C writes with interrupts disabled | expand |
* Stefan Lengfeld <contact@stefanchrist.eu> [180813 21:19]: > Using i2c_transfer() to set the shutdown bit is more reliable than using > regmap. Furthermore you have to void the default lock configuration in > the regmap configuration, e.g. by setting use_hwlock to true, to used in > atomic/IRQ disabled contexts. Hmm so this is a bit worrying, does this mean that regmap can't deal with atomic i2c then? Regards, Tony
Hi Tony, On Mon, Aug 20, 2018 at 07:55:22AM -0700, Tony Lindgren wrote: > * Stefan Lengfeld <contact@stefanchrist.eu> [180813 21:19]: > > Using i2c_transfer() to set the shutdown bit is more reliable than using > > regmap. Furthermore you have to void the default lock configuration in > > the regmap configuration, e.g. by setting use_hwlock to true, to used in > > atomic/IRQ disabled contexts. > > Hmm so this is a bit worrying, does this mean that regmap can't deal > with atomic i2c then? In theory yes. Regmap can support IRQ/sleep less operation, but you have to ensure that the whole callstack trough the regmap interface and code never calls sleep or waits for a lock. First you have to use a sleep-less lock/unlock implementation in the regmap_config e.g. static struct regmap_config da9062_regmap_config = { [...] /* Enable hwclock to use a sleep-free lock implementation */ .use_hwlock = 1, Or providing an own implementations of the regmap callbacks struct regmap_config { [...] regmap_lock lock; regmap_unlock unlock; If have tried that and tested the code with CONFIG_DEBUG_ATOMIC_SLEEP But I have still seen a sleep violation in the regmap cache implementation. Somewhere a cache handler was acquiring a lock or made a memory allocation. At that point I gave up and just called the I²C interface directly. So I would say, regmap can support atomic I²C transfers, but you need a lot of tweaking and on device testing. Kind regards, Stefan
diff --git a/drivers/mfd/da9062-core.c b/drivers/mfd/da9062-core.c index 9f6105906c09..b6a01054ba0f 100644 --- a/drivers/mfd/da9062-core.c +++ b/drivers/mfd/da9062-core.c @@ -609,6 +609,7 @@ static int da9062_i2c_probe(struct i2c_client *i2c, i2c_set_clientdata(i2c, chip); chip->dev = &i2c->dev; + chip->i2c = i2c; if (!i2c->irq) { dev_err(chip->dev, "No IRQ configured\n"); diff --git a/drivers/watchdog/da9062_wdt.c b/drivers/watchdog/da9062_wdt.c index fe169d8e1fb2..ad6483d25f83 100644 --- a/drivers/watchdog/da9062_wdt.c +++ b/drivers/watchdog/da9062_wdt.c @@ -11,6 +11,7 @@ #include <linux/platform_device.h> #include <linux/uaccess.h> #include <linux/slab.h> +#include <linux/i2c.h> #include <linux/delay.h> #include <linux/jiffies.h> #include <linux/mfd/da9062/registers.h> @@ -152,12 +153,20 @@ static int da9062_wdt_restart(struct watchdog_device *wdd, unsigned long action, void *data) { struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd); + struct i2c_client *client = wdt->hw->i2c; + __u8 buf[3] = {DA9062AA_CONTROL_F, DA9062AA_SHUTDOWN_MASK, 0x0}; + struct i2c_msg msgs[1] = { + { + .addr = client->addr, + .flags = (client->flags & I2C_M_TEN), + .len = sizeof(buf), + .buf = buf, + } + }; int ret; - ret = regmap_write(wdt->hw->regmap, - DA9062AA_CONTROL_F, - DA9062AA_SHUTDOWN_MASK); - if (ret) + ret = i2c_transfer(client->adapter, msgs, sizeof(msgs)); + if (ret < 0) dev_alert(wdt->hw->dev, "Failed to shutdown (err = %d)\n", ret); diff --git a/include/linux/mfd/da9062/core.h b/include/linux/mfd/da9062/core.h index 74d33a01ddae..c994293b3aef 100644 --- a/include/linux/mfd/da9062/core.h +++ b/include/linux/mfd/da9062/core.h @@ -68,6 +68,7 @@ enum da9062_irqs { struct da9062 { struct device *dev; struct regmap *regmap; + struct i2c_client *i2c; struct regmap_irq_chip_data *regmap_irq; enum da9062_compatible_types chip_type; };
Using i2c_transfer() to set the shutdown bit is more reliable than using regmap. Furthermore you have to void the default lock configuration in the regmap configuration, e.g. by setting use_hwlock to true, to used in atomic/IRQ disabled contexts. Tested on a phyCORE-i.MX6 Solo board. Signed-off-by: Stefan Lengfeld <contact@stefanchrist.eu> --- drivers/mfd/da9062-core.c | 1 + drivers/watchdog/da9062_wdt.c | 17 +++++++++++++---- include/linux/mfd/da9062/core.h | 1 + 3 files changed, 15 insertions(+), 4 deletions(-)