pwm: Make info in traces about affected pwm more useful

[PATCH] pwm: Make info in traces about affected pwm more useful

Posted by Uwe Kleine-König 1 year, 7 months ago

The hashed pointer isn't useful to identify the pwm device. Instead
store and emit chipid and hwpwm.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
---
 include/trace/events/pwm.h | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/include/trace/events/pwm.h b/include/trace/events/pwm.h
index 12b35e4ff917..8022701c446d 100644
--- a/include/trace/events/pwm.h
+++ b/include/trace/events/pwm.h
@@ -15,7 +15,8 @@ DECLARE_EVENT_CLASS(pwm,
 	TP_ARGS(pwm, state, err),
 
 	TP_STRUCT__entry(
-		__field(struct pwm_device *, pwm)
+		__field(unsigned int, chipid)
+		__field(unsigned int, hwpwm)
 		__field(u64, period)
 		__field(u64, duty_cycle)
 		__field(enum pwm_polarity, polarity)
@@ -24,7 +25,8 @@ DECLARE_EVENT_CLASS(pwm,
 	),
 
 	TP_fast_assign(
-		__entry->pwm = pwm;
+		__entry->chipid = pwm->chip->id;
+		__entry->hwpwm = pwm->hwpwm;
 		__entry->period = state->period;
 		__entry->duty_cycle = state->duty_cycle;
 		__entry->polarity = state->polarity;
@@ -32,8 +34,8 @@ DECLARE_EVENT_CLASS(pwm,
 		__entry->err = err;
 	),
 
-	TP_printk("%p: period=%llu duty_cycle=%llu polarity=%d enabled=%d err=%d",
-		  __entry->pwm, __entry->period, __entry->duty_cycle,
+	TP_printk("pwmchip%u.%u: period=%llu duty_cycle=%llu polarity=%d enabled=%d err=%d",
+		  __entry->chipid, __entry->hwpwm, __entry->period, __entry->duty_cycle,
 		  __entry->polarity, __entry->enabled, __entry->err)
 
 );

base-commit: 6ba37c70795abf1d59976b3a49acafac14b72a4f
-- 
2.43.0

Re: [PATCH] pwm: Make info in traces about affected pwm more useful

Posted by Uwe Kleine-König 1 year, 6 months ago

Hello,

On Fri, Jul 05, 2024 at 11:14:51PM +0200, Uwe Kleine-König wrote:
> The hashed pointer isn't useful to identify the pwm device. Instead
> store and emit chipid and hwpwm.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
> ---
>  include/trace/events/pwm.h | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/include/trace/events/pwm.h b/include/trace/events/pwm.h
> index 12b35e4ff917..8022701c446d 100644
> --- a/include/trace/events/pwm.h
> +++ b/include/trace/events/pwm.h
> @@ -15,7 +15,8 @@ DECLARE_EVENT_CLASS(pwm,
>  	TP_ARGS(pwm, state, err),
>  
>  	TP_STRUCT__entry(
> -		__field(struct pwm_device *, pwm)
> +		__field(unsigned int, chipid)
> +		__field(unsigned int, hwpwm)
>  		__field(u64, period)
>  		__field(u64, duty_cycle)
>  		__field(enum pwm_polarity, polarity)
> @@ -24,7 +25,8 @@ DECLARE_EVENT_CLASS(pwm,
>  	),
>  
>  	TP_fast_assign(
> -		__entry->pwm = pwm;
> +		__entry->chipid = pwm->chip->id;
> +		__entry->hwpwm = pwm->hwpwm;
>  		__entry->period = state->period;
>  		__entry->duty_cycle = state->duty_cycle;
>  		__entry->polarity = state->polarity;
> @@ -32,8 +34,8 @@ DECLARE_EVENT_CLASS(pwm,
>  		__entry->err = err;
>  	),
>  
> -	TP_printk("%p: period=%llu duty_cycle=%llu polarity=%d enabled=%d err=%d",
> -		  __entry->pwm, __entry->period, __entry->duty_cycle,
> +	TP_printk("pwmchip%u.%u: period=%llu duty_cycle=%llu polarity=%d enabled=%d err=%d",
> +		  __entry->chipid, __entry->hwpwm, __entry->period, __entry->duty_cycle,
>  		  __entry->polarity, __entry->enabled, __entry->err)
>  
>  );

I think the patch is obvious enough to be ok even without the tracing
maintainer's blessing. I applied it to
https://git.kernel.org/pub/scm/linux/kernel/git/ukleinek/linux.git pwm/for-next
.

Best regards
Uwe

Re: [PATCH] pwm: Make info in traces about affected pwm more useful

Posted by Steven Rostedt 1 year, 6 months ago

On Tue, 30 Jul 2024 09:22:53 +0200
Uwe Kleine-König <u.kleine-koenig@baylibre.com> wrote:

> I think the patch is obvious enough to be ok even without the tracing
> maintainer's blessing. I applied it to
> https://git.kernel.org/pub/scm/linux/kernel/git/ukleinek/linux.git pwm/for-next
> .

No problem. Thanks for the Cc. I don't always reply if the patch is pretty
straight forward. But I do look for things like holes in the TP_struct()
portion, that would waste ring buffer space. As well as uses of
dereferencing pointers.

-- Steve

Re: [PATCH] pwm: Make info in traces about affected pwm more useful

Posted by Uwe Kleine-König 1 year, 6 months ago

On Tue, Jul 30, 2024 at 10:39:10AM -0400, Steven Rostedt wrote:
> On Tue, 30 Jul 2024 09:22:53 +0200
> Uwe Kleine-König <u.kleine-koenig@baylibre.com> wrote:
> 
> > I think the patch is obvious enough to be ok even without the tracing
> > maintainer's blessing. I applied it to
> > https://git.kernel.org/pub/scm/linux/kernel/git/ukleinek/linux.git pwm/for-next
> > .
> 
> No problem. Thanks for the Cc. I don't always reply if the patch is pretty
> straight forward. But I do look for things like holes in the TP_struct()
> portion, that would waste ring buffer space. As well as uses of
> dereferencing pointers.

Looking at
https://lore.kernel.org/linux-pwm/7b9c9ee490df1df1de3bbfafd501f45c6cb2ec4c.1722261050.git.u.kleine-koenig@baylibre.com
is this also in the "straight forward" category? If not, some feedback
would be appreciated there.

Thanks
Uwe