Re: [PATCH v2] drm/i915/selftests: Correct frequency handling in RPS power measurement

["Nilawar, Badal" <badal.nilawar@xxxxxxxxx>]

On 09-01-2025 15:50, Nilawar, Badal wrote:

On 09-01-2025 15:00, sk.anirban@xxxxxxxxx wrote:

From: Sk Anirban <sk.anirban@xxxxxxxxx>

Fix the frequency calculation by ensuring it is adjusted
only once during power measurement. Update live_rps_power test
to use the correct frequency values for logging and comparison.

v2:
  - Improved frequency logging (Riana)

Signed-off-by: Sk Anirban <sk.anirban@xxxxxxxxx>
Reviewed-by: Riana Tauro <riana.tauro@xxxxxxxxx>
---
 drivers/gpu/drm/i915/gt/selftest_rps.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/selftest_rps.c b/drivers/gpu/drm/i915/gt/selftest_rps.c
index c207a4fb03bf..e515d7eb628a 100644
--- a/drivers/gpu/drm/i915/gt/selftest_rps.c
+++ b/drivers/gpu/drm/i915/gt/selftest_rps.c
@@ -1126,6 +1126,7 @@ static u64 measure_power_at(struct intel_rps *rps, int *freq)
 {
 	*freq = rps_set_check(rps, *freq);
 	msleep(100);
+	*freq = intel_gpu_freq(rps, *freq);

I am seeing rps_set_check will wait till act freq become desired freq, in case of timeout act freq could be different.
I think it would be good to check freq returned by rps_set_check is expected freq if not then read freq again after msleep.

Please ignore above comments, I got your code. You are applying freq multiplier before passing to measure_power. While this approach works fine, I recommend fixing measure_power() by using read_cagf() instead of intel_rps_read_actual_frequency().
Add Fixes: ac4e8560248f ("drm/i915/selftests: Add helper function measure_power") in commit message.

Regards,
Badal

> Regards,
> Badal
>
> >  	return measure_power(rps, freq);
> >  }
> >  
> > @@ -1202,13 +1203,13 @@ int live_rps_power(void *arg)
> >  
> >  		pr_info("%s: min:%llumW @ %uMHz, max:%llumW @ %uMHz\n",
> >  			engine->name,
> > -			min.power, intel_gpu_freq(rps, min.freq),
> > -			max.power, intel_gpu_freq(rps, max.freq));
> > +			min.power, min.freq,
> > +			max.power, max.freq);
> >  
> >  		if (10 * min.freq >= 9 * max.freq) {
> > -			pr_notice("Could not control frequency, ran at [%d:%uMHz, %d:%uMhz]\n",
> > -				  min.freq, intel_gpu_freq(rps, min.freq),
> > -				  max.freq, intel_gpu_freq(rps, max.freq));
> > +			pr_notice("Could not control frequency, ran at [%uMHz, %uMhz]\n",
> > +				  min.freq,
> > +				  max.freq);
> >  			continue;
> >  		}
> >  
> >       
>