Re: [Intel-gfx] [PATCH 2/2] drm/i915/pmu: Remove fallback to requested freq for SLPC
On Wed, 15 Mar 2023 02:50:17 -0700, Tvrtko Ursulin wrote: > > On 10/03/2023 00:59, Ashutosh Dixit wrote: > > The fallback to requested freq does not work for SLPC because SLPC does not > > use 'struct intel_rps'. Also for SLPC requested freq can only be obtained > > from a hw register after acquiring forcewake which we don't want to do for > > PMU. Therefore remove fallback to requested freq for SLPC. The actual freq > > will be 0 when gt is in RC6 which is correct. Also this is rare since PMU > > freq sampling happens only when gt is unparked. > > > > Signed-off-by: Ashutosh Dixit > > --- > > drivers/gpu/drm/i915/i915_pmu.c | 9 - > > 1 file changed, 8 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/i915/i915_pmu.c > > b/drivers/gpu/drm/i915/i915_pmu.c > > index 7ece883a7d95..f697fabed64a 100644 > > --- a/drivers/gpu/drm/i915/i915_pmu.c > > +++ b/drivers/gpu/drm/i915/i915_pmu.c > > @@ -393,7 +393,14 @@ frequency_sample(struct intel_gt *gt, unsigned int > > period_ns) > > * frequency. Fortunately, the read should rarely fail! > > */ > > val = intel_rps_read_actual_frequency_fw(rps); > > - if (!val) > > + > > + /* > > +* SLPC does not use 'struct intel_rps'. Also for SLPC > > +* requested freq can only be obtained after acquiring > > +* forcewake and reading a hw register. For SLPC just > > +* let val be 0 > > +*/ > > + if (!val && !intel_uc_uses_guc_slpc(>uc)) > > val = intel_gpu_freq(rps, rps->cur_freq); > > I really dislike sprinkling of "uses slpc" since I think the thing hasn't > really been integrated nicely. Case in point is probably the flow duality > in intel_rps_boost. Data structures as well, even though some fields and > concepts are shared. > > For instance why we can't have the notion of software tracked cur_freq in > rps, and/or have it zero if with SLPC we can't have it otherwise? For SLPC: * We can't have the notion of software tracked cur_freq in rps because FW is managing the freq. * rps->cur_freq /is/ actually 0 since SLPC does not use 'struct intel_rps'. So this patch doesn't really make any practical difference, PMU values will be exactly the same with or without this patch. It was just clarifying things. > I will abstain, sorry. I will drop this patch, there doesn't seem much point in it. Thanks. -- Ashutosh
Re: [Intel-gfx] [PATCH 2/2] drm/i915/pmu: Remove fallback to requested freq for SLPC
On 10/03/2023 00:59, Ashutosh Dixit wrote: The fallback to requested freq does not work for SLPC because SLPC does not use 'struct intel_rps'. Also for SLPC requested freq can only be obtained from a hw register after acquiring forcewake which we don't want to do for PMU. Therefore remove fallback to requested freq for SLPC. The actual freq will be 0 when gt is in RC6 which is correct. Also this is rare since PMU freq sampling happens only when gt is unparked. Signed-off-by: Ashutosh Dixit --- drivers/gpu/drm/i915/i915_pmu.c | 9 - 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c index 7ece883a7d95..f697fabed64a 100644 --- a/drivers/gpu/drm/i915/i915_pmu.c +++ b/drivers/gpu/drm/i915/i915_pmu.c @@ -393,7 +393,14 @@ frequency_sample(struct intel_gt *gt, unsigned int period_ns) * frequency. Fortunately, the read should rarely fail! */ val = intel_rps_read_actual_frequency_fw(rps); - if (!val) + + /* +* SLPC does not use 'struct intel_rps'. Also for SLPC +* requested freq can only be obtained after acquiring +* forcewake and reading a hw register. For SLPC just +* let val be 0 +*/ + if (!val && !intel_uc_uses_guc_slpc(>uc)) val = intel_gpu_freq(rps, rps->cur_freq); I really dislike sprinkling of "uses slpc" since I think the thing hasn't really been integrated nicely. Case in point is probably the flow duality in intel_rps_boost. Data structures as well, even though some fields and concepts are shared. For instance why we can't have the notion of software tracked cur_freq in rps, and/or have it zero if with SLPC we can't have it otherwise? I will abstain, sorry. Regards, Tvrtko add_sample_mult(>sample[__I915_SAMPLE_FREQ_ACT],
[Intel-gfx] [PATCH 2/2] drm/i915/pmu: Remove fallback to requested freq for SLPC
The fallback to requested freq does not work for SLPC because SLPC does not use 'struct intel_rps'. Also for SLPC requested freq can only be obtained from a hw register after acquiring forcewake which we don't want to do for PMU. Therefore remove fallback to requested freq for SLPC. The actual freq will be 0 when gt is in RC6 which is correct. Also this is rare since PMU freq sampling happens only when gt is unparked. Signed-off-by: Ashutosh Dixit --- drivers/gpu/drm/i915/i915_pmu.c | 9 - 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c index 7ece883a7d95..f697fabed64a 100644 --- a/drivers/gpu/drm/i915/i915_pmu.c +++ b/drivers/gpu/drm/i915/i915_pmu.c @@ -393,7 +393,14 @@ frequency_sample(struct intel_gt *gt, unsigned int period_ns) * frequency. Fortunately, the read should rarely fail! */ val = intel_rps_read_actual_frequency_fw(rps); - if (!val) + + /* +* SLPC does not use 'struct intel_rps'. Also for SLPC +* requested freq can only be obtained after acquiring +* forcewake and reading a hw register. For SLPC just +* let val be 0 +*/ + if (!val && !intel_uc_uses_guc_slpc(>uc)) val = intel_gpu_freq(rps, rps->cur_freq); add_sample_mult(>sample[__I915_SAMPLE_FREQ_ACT], -- 2.38.0
[Intel-gfx] [PATCH 2/2] drm/i915/pmu: Remove fallback to requested freq for SLPC
The fallback to requested freq does not work for SLPC because SLPC does not use 'struct intel_rps'. Also for SLPC requested freq can only be obtained from a hw register after acquiring forcewake which we don't want to do for PMU. Therefore remove fallback to requested freq for SLPC. The actual freq will be 0 when gt is in RC6 which is correct. Also this is rare since PMU freq sampling happens only when gt is unparked. Signed-off-by: Ashutosh Dixit --- drivers/gpu/drm/i915/i915_pmu.c | 9 - 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c index 7ece883a7d95..f697fabed64a 100644 --- a/drivers/gpu/drm/i915/i915_pmu.c +++ b/drivers/gpu/drm/i915/i915_pmu.c @@ -393,7 +393,14 @@ frequency_sample(struct intel_gt *gt, unsigned int period_ns) * frequency. Fortunately, the read should rarely fail! */ val = intel_rps_read_actual_frequency_fw(rps); - if (!val) + + /* +* SLPC does not use 'struct intel_rps'. Also for SLPC +* requested freq can only be obtained after acquiring +* forcewake and reading a hw register. For SLPC just +* let val be 0 +*/ + if (!val && !intel_uc_uses_guc_slpc(>uc)) val = intel_gpu_freq(rps, rps->cur_freq); add_sample_mult(>sample[__I915_SAMPLE_FREQ_ACT], -- 2.38.0
