Re: [PATCH v3] drm/i915/selftest: Add throttle reason diagnostics to RPS selftests

["Anirban, Sk" <sk.anirban@intel.com>]

Hi Krzysztof,

Could you please let me know if I can retain your review for this 
version of my patch?

Thanks,

Anirban

On 18-12-2025 11:02 am, Sk Anirban wrote:
> Report GPU throttle reasons when RPS tests fail to reach expected
> frequencies or power levels.
>
> v2: Read the throttle value before the spinner ends (Raag)
>      Add a condition before printing throttle value (Krzysztof)
> v3: Extend throttle reasons debug support (Raag)
>
> Signed-off-by: Sk Anirban <sk.anirban@intel.com>
> ---
>   drivers/gpu/drm/i915/gt/selftest_rps.c | 37 ++++++++++++++++++++++----
>   1 file changed, 32 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/selftest_rps.c b/drivers/gpu/drm/i915/gt/selftest_rps.c
> index 73bc91c6ea07..b42d9b39add6 100644
> --- a/drivers/gpu/drm/i915/gt/selftest_rps.c
> +++ b/drivers/gpu/drm/i915/gt/selftest_rps.c
> @@ -378,6 +378,7 @@ int live_rps_control(void *arg)
>   	enum intel_engine_id id;
>   	struct igt_spinner spin;
>   	intel_wakeref_t wakeref;
> +	u32 throttle;
>   	int err = 0;
>   
>   	/*
> @@ -463,6 +464,10 @@ int live_rps_control(void *arg)
>   		max = rps_set_check(rps, limit);
>   		max_dt = ktime_sub(ktime_get(), max_dt);
>   
> +		throttle = intel_uncore_read(gt->uncore,
> +					     intel_gt_perf_limit_reasons_reg(gt));
> +		throttle &= GT0_PERF_LIMIT_REASONS_MASK;
> +
>   		min_dt = ktime_get();
>   		min = rps_set_check(rps, rps->min_freq);
>   		min_dt = ktime_sub(ktime_get(), min_dt);
> @@ -478,11 +483,9 @@ int live_rps_control(void *arg)
>   			min, max, ktime_to_ns(min_dt), ktime_to_ns(max_dt));
>   
>   		if (limit != rps->max_freq) {
> -			u32 throttle = intel_uncore_read(gt->uncore,
> -							 intel_gt_perf_limit_reasons_reg(gt));
> -
> -			pr_warn("%s: GPU throttled with reasons 0x%08x\n",
> -				engine->name, throttle & GT0_PERF_LIMIT_REASONS_MASK);
> +			if (throttle)
> +				pr_warn("%s: GPU throttled with reasons 0x%08x\n",
> +					engine->name, throttle);
>   			show_pstate_limits(rps);
>   		}
>   
> @@ -1138,6 +1141,7 @@ int live_rps_power(void *arg)
>   	struct intel_engine_cs *engine;
>   	enum intel_engine_id id;
>   	struct igt_spinner spin;
> +	u32 throttle;
>   	int err = 0;
>   
>   	/*
> @@ -1195,6 +1199,10 @@ int live_rps_power(void *arg)
>   		max.freq = rps->max_freq;
>   		max.power = measure_power_at(rps, &max.freq);
>   
> +		throttle = intel_uncore_read(gt->uncore,
> +					     intel_gt_perf_limit_reasons_reg(gt));
> +		throttle &= GT0_PERF_LIMIT_REASONS_MASK;
> +
>   		min.freq = rps->min_freq;
>   		min.power = measure_power_at(rps, &min.freq);
>   
> @@ -1210,12 +1218,21 @@ int live_rps_power(void *arg)
>   			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));
> +
> +			if (throttle)
> +				pr_warn("%s: GPU throttled with reasons 0x%08x\n",
> +					engine->name, throttle);
>   			continue;
>   		}
>   
>   		if (11 * min.power > 10 * max.power) {
>   			pr_err("%s: did not conserve power when setting lower frequency!\n",
>   			       engine->name);
> +
> +			if (throttle)
> +				pr_warn("%s: GPU throttled with reasons 0x%08x\n",
> +					engine->name, throttle);
> +
>   			err = -EINVAL;
>   			break;
>   		}
> @@ -1241,6 +1258,7 @@ int live_rps_dynamic(void *arg)
>   	struct intel_engine_cs *engine;
>   	enum intel_engine_id id;
>   	struct igt_spinner spin;
> +	u32 throttle;
>   	int err = 0;
>   
>   	/*
> @@ -1293,6 +1311,10 @@ int live_rps_dynamic(void *arg)
>   		max.freq = wait_for_freq(rps, rps->max_freq, 500);
>   		max.dt = ktime_sub(ktime_get(), max.dt);
>   
> +		throttle = intel_uncore_read(gt->uncore,
> +					     intel_gt_perf_limit_reasons_reg(gt));
> +		throttle &= GT0_PERF_LIMIT_REASONS_MASK;
> +
>   		igt_spinner_end(&spin);
>   
>   		min.dt = ktime_get();
> @@ -1308,6 +1330,11 @@ int live_rps_dynamic(void *arg)
>   		if (min.freq >= max.freq) {
>   			pr_err("%s: dynamic reclocking of spinner failed\n!",
>   			       engine->name);
> +
> +			if (throttle)
> +				pr_warn("%s: GPU throttled with reasons 0x%08x\n",
> +					engine->name, throttle);
> +
>   			err = -EINVAL;
>   		}
>