| Message ID | 20210819121403.337833-1-u.kleine-koenig@pengutronix.de (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
| Series | [v2] clk: expand clk_ignore_unused mechanism to keep only a few clks on | expand |
Hello, On Thu, Aug 19, 2021 at 02:14:03PM +0200, Uwe Kleine-König wrote: > Allow to pass an integer n that results in only keeping n unused clocks > enabled. > > This helps to debug the problem if you only know that clk_ignore_unused > helps but you have no clue yet which clock is the culprit. > > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> I consider this patch really helpful, it helped me to debug a clk issue without having to recompile the kernel for each bisection step. On #kernelnewbies I got some positive feedback for it (1629304050 < j_ey> ukleinek: nice clk_ignore_unused patch, I added a pr_err there recently to print the clocks that were being disabled). Best regards Uwe
Hello, On Wed, Sep 22, 2021 at 10:15:49AM +0200, Uwe Kleine-König wrote: > On Thu, Aug 19, 2021 at 02:14:03PM +0200, Uwe Kleine-König wrote: > > Allow to pass an integer n that results in only keeping n unused clocks > > enabled. > > > > This helps to debug the problem if you only know that clk_ignore_unused > > helps but you have no clue yet which clock is the culprit. > > > > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> > > I consider this patch really helpful, it helped me to debug a clk issue > without having to recompile the kernel for each bisection step. > > On #kernelnewbies I got some positive feedback for it (1629304050 < j_ey> > ukleinek: nice clk_ignore_unused patch, I added a pr_err there recently > to print the clocks that were being disabled). Any thoughts on this patch? Would be great if it makes it into the next merge window. Thanks for considering, Uwe
On Thu, Oct 14, 2021 at 05:43:07PM +0200, Uwe Kleine-König wrote: > Hello, > > On Wed, Sep 22, 2021 at 10:15:49AM +0200, Uwe Kleine-König wrote: > > On Thu, Aug 19, 2021 at 02:14:03PM +0200, Uwe Kleine-König wrote: > > > Allow to pass an integer n that results in only keeping n unused clocks > > > enabled. > > > > > > This helps to debug the problem if you only know that clk_ignore_unused > > > helps but you have no clue yet which clock is the culprit. > > > > > > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> > > > > I consider this patch really helpful, it helped me to debug a clk issue > > without having to recompile the kernel for each bisection step. > > > > On #kernelnewbies I got some positive feedback for it (1629304050 < j_ey> > > ukleinek: nice clk_ignore_unused patch, I added a pr_err there recently > > to print the clocks that were being disabled). > > Any thoughts on this patch? Would be great if it makes it into the next > merge window. Back then I thought this patch could make it into 5.16, now 5.18 is released and i didn't get any feedback on this patch :-\ Best regards Uwe
diff --git a/Documentation/driver-api/clk.rst b/Documentation/driver-api/clk.rst index 3cad45d14187..65ae7c3e2b33 100644 --- a/Documentation/driver-api/clk.rst +++ b/Documentation/driver-api/clk.rst @@ -259,7 +259,9 @@ the disabling means that the driver will remain functional while the issues are sorted out. To bypass this disabling, include "clk_ignore_unused" in the bootargs to the -kernel. +kernel. If you pass "clk_ignore_unused=n" (where n is an integer) the first n +found clocks are not disabled which can be useful for bisecting over the unused +clks if you don't know yet which of them is reponsible for your problem. Locking ======= diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 65508eb89ec9..afa9f9397ddb 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -1236,6 +1236,8 @@ static void __init clk_unprepare_unused_subtree(struct clk_core *core) clk_pm_runtime_put(core); } +static unsigned clk_unused_keep_on __initdata; + static void __init clk_disable_unused_subtree(struct clk_core *core) { struct clk_core *child; @@ -1266,12 +1268,17 @@ static void __init clk_disable_unused_subtree(struct clk_core *core) * back to .disable */ if (clk_core_is_enabled(core)) { - trace_clk_disable(core); - if (core->ops->disable_unused) - core->ops->disable_unused(core->hw); - else if (core->ops->disable) - core->ops->disable(core->hw); - trace_clk_disable_complete(core); + if (clk_unused_keep_on) { + pr_warn("Keep unused clk \"%s\" on\n", core->name); + clk_unused_keep_on -= 1; + } else { + trace_clk_disable(core); + if (core->ops->disable_unused) + core->ops->disable_unused(core->hw); + else if (core->ops->disable) + core->ops->disable(core->hw); + trace_clk_disable_complete(core); + } } unlock_out: @@ -1283,9 +1290,17 @@ static void __init clk_disable_unused_subtree(struct clk_core *core) } static bool clk_ignore_unused __initdata; -static int __init clk_ignore_unused_setup(char *__unused) +static int __init clk_ignore_unused_setup(char *keep) { - clk_ignore_unused = true; + if (*keep == '=') { + int ret; + + ret = kstrtouint(keep + 1, 0, &clk_unused_keep_on); + if (ret < 0) + pr_err("Warning: failed to parse clk_ignore_unused parameter, ignoring"); + } else { + clk_ignore_unused = true; + } return 1; } __setup("clk_ignore_unused", clk_ignore_unused_setup); @@ -1297,6 +1312,8 @@ static int __init clk_disable_unused(void) if (clk_ignore_unused) { pr_warn("clk: Not disabling unused clocks\n"); return 0; + } else if (clk_unused_keep_on) { + pr_warn("clk: Not disabling %u unused clocks\n", clk_unused_keep_on); } clk_prepare_lock();
Allow to pass an integer n that results in only keeping n unused clocks enabled. This helps to debug the problem if you only know that clk_ignore_unused helps but you have no clue yet which clock is the culprit. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> --- Hello, Interdiff against (implicit) v1: diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 7189a56bb29f..afa9f9397ddb 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -1312,8 +1312,8 @@ static int __init clk_disable_unused(void) if (clk_ignore_unused) { pr_warn("clk: Not disabling unused clocks\n"); return 0; - } else if (clk_ignore_unused) { - pr_warn("clk: Not disabling %u unused clocks\n", clk_ignore_unused); + } else if (clk_unused_keep_on) { + pr_warn("clk: Not disabling %u unused clocks\n", clk_unused_keep_on); } clk_prepare_lock(); which fixes the debug output. Found by the kernel test robot; Thanks! Best regards Uwe Documentation/driver-api/clk.rst | 4 +++- drivers/clk/clk.c | 33 ++++++++++++++++++++++++-------- 2 files changed, 28 insertions(+), 9 deletions(-)