Re: [Freedreno] [PATCH 5/6] drm/msm/a6xx: Use GMU_ALWAYS_ON_COUNTER for GMU-equipped GPUs in timestamp

[Jonathan Marek]

On 5/17/23 3:08 PM, Konrad Dybcio wrote:
> On 17.05.2023 20:09, Jonathan Marek wrote:
> > AFAIK GMU_ALWAYS_ON_COUNTER does not have the same value as CP_ALWAYS_ON_COUNTER (only the same frequency), so changing this would break userspace expecting to be able to compare the value returned by MSM_PARAM_TIMESTAMP with CP timestamp values.
> FWIW A630 and A730 seem to work fine with this patch. Anything
> in particular I should look out for?

mesa uses it for perfetto tracing to synchronize the GPU/CPU timelines.

> Konrad
> > On 5/17/23 12:50 PM, Konrad Dybcio wrote:
> > > Use the always-on counter provided by the GMU to skip having to
> > > keep the GPU online.
> > >
> > > Signed-off-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxx>
> > > ---
> > >    drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 9 +++------
> > >    1 file changed, 3 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> > > index 8707e8b6ac7e..d2a999b90589 100644
> > > --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> > > +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> > > @@ -1664,12 +1664,9 @@ static int a6xx_get_timestamp(struct msm_gpu *gpu, uint64_t *value)
> > >          mutex_lock(&a6xx_gpu->gmu.lock);
> > >    -    /* Force the GPU power on so we can read this register */
> > > -    a6xx_gmu_set_oob(&a6xx_gpu->gmu, GMU_OOB_PERFCOUNTER_SET);
> > > -
> > > -    *value = gpu_read64(gpu, REG_A6XX_CP_ALWAYS_ON_COUNTER);
> > > -
> > > -    a6xx_gmu_clear_oob(&a6xx_gpu->gmu, GMU_OOB_PERFCOUNTER_SET);
> > > +    *value = gmu_read64(&a6xx_gpu->gmu,
> > > +                REG_A6XX_GMU_ALWAYS_ON_COUNTER_L,
> > > +                REG_A6XX_GMU_ALWAYS_ON_COUNTER_H);
> > >          mutex_unlock(&a6xx_gpu->gmu.lock);
> > >