Re: [PATCH] drm/msm: Grab the GPU runtime in a6xx routines, not the GMU one

Akhil P Oommen <quic_akhilpo@xxxxxxxxxxx> · Thu, 9 Jun 2022 21:34:58 +0530

On 6/9/2022 9:24 PM, Rob Clark wrote:
On Thu, Jun 9, 2022 at 7:34 AM Douglas Anderson <dianders@xxxxxxxxxxxx> wrote:
 From testing on sc7180-trogdor devices, reading the GMU registers
needs the GMU clocks to be enabled. Those clocks get turned on in
a6xx_gmu_resume(). Confusingly enough, that function is called as a
result of the runtime_pm of the GPU "struct device", not the GMU
"struct device".

Let's grab a reference to the correct device. Incidentally, this makes
us match the a5xx routine more closely.

This is easily shown to fix crashes that happen if we change the GPU's
pm_runtime usage to not use autosuspend. It's also believed to fix
some long tail GPU crashes even with autosuspend.

NOTE: the crashes I've seen were fixed by _only_ fixing
a6xx_gpu_busy(). However, I believe that the same arguments should be
made to a6xx_gmu_set_freq() so I've changed that function too.

Fixes: eadf79286a4b ("drm/msm: Check for powered down HW in the devfreq callbacks")
Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
---

  drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 6 +++---
  drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 4 ++--
  2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
index 9f76f5b15759..b79ad2e0649c 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
@@ -129,13 +129,13 @@ void a6xx_gmu_set_freq(struct msm_gpu *gpu, struct dev_pm_opp *opp)
          * This can get called from devfreq while the hardware is idle. Don't
          * bring up the power if it isn't already active
          */
-       if (pm_runtime_get_if_in_use(gmu->dev) == 0)
+       if (pm_runtime_get_if_in_use(&gpu->pdev->dev) == 0)
IMHO, if we do end up using the GPU's runpm instead of the GMU's, we
should probably just move this _get_if_in_use() into msm_gpu_devfreq,
+ 1 this.
etc.  (And probably also this should be "<= 0".. I have that change
locally but haven't sent a patch yet
.. and skip return here when CONFIG_PM is disabled.

-Akhil.

BR,
-R

                 return;

         if (!gmu->legacy) {
                 a6xx_hfi_set_freq(gmu, perf_index);
                 dev_pm_opp_set_opp(&gpu->pdev->dev, opp);
-               pm_runtime_put(gmu->dev);
+               pm_runtime_put(&gpu->pdev->dev);
                 return;
         }

@@ -159,7 +159,7 @@ void a6xx_gmu_set_freq(struct msm_gpu *gpu, struct dev_pm_opp *opp)
                 dev_err(gmu->dev, "GMU set GPU frequency error: %d\n", ret);

         dev_pm_opp_set_opp(&gpu->pdev->dev, opp);
-       pm_runtime_put(gmu->dev);
+       pm_runtime_put(&gpu->pdev->dev);
  }

  unsigned long a6xx_gmu_get_freq(struct msm_gpu *gpu)
diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index 841e47a0b06b..87568d0b6ef8 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -1659,7 +1659,7 @@ static u64 a6xx_gpu_busy(struct msm_gpu *gpu, unsigned long *out_sample_rate)
         *out_sample_rate = 19200000;

         /* Only read the gpu busy if the hardware is already active */
-       if (pm_runtime_get_if_in_use(a6xx_gpu->gmu.dev) == 0)
+       if (pm_runtime_get_if_in_use(&gpu->pdev->dev) == 0)
                 return 0;

         busy_cycles = gmu_read64(&a6xx_gpu->gmu,
@@ -1667,7 +1667,7 @@ static u64 a6xx_gpu_busy(struct msm_gpu *gpu, unsigned long *out_sample_rate)
                         REG_A6XX_GMU_CX_GMU_POWER_COUNTER_XOCLK_0_H);


-       pm_runtime_put(a6xx_gpu->gmu.dev);
+       pm_runtime_put(&gpu->pdev->dev);

         return busy_cycles;
  }
--
2.36.1.255.ge46751e96f-goog








