On Mon, Jul 11, 2022 at 10:05 PM Akhil P Oommen <quic_akhilpo@xxxxxxxxxxx> wrote: > > On 7/12/2022 4:52 AM, Doug Anderson wrote: > > Hi, > > > > On Fri, Jul 8, 2022 at 11:00 PM Akhil P Oommen <quic_akhilpo@xxxxxxxxxxx> wrote: > >> There are some hardware logic under CX domain. For a successful > >> recovery, we should ensure cx headswitch collapses to ensure all the > >> stale states are cleard out. This is especially true to for a6xx family > >> where we can GMU co-processor. > >> > >> Currently, cx doesn't collapse due to a devlink between gpu and its > >> smmu. So the *struct gpu device* needs to be runtime suspended to ensure > >> that the iommu driver removes its vote on cx gdsc. > >> > >> Signed-off-by: Akhil P Oommen <quic_akhilpo@xxxxxxxxxxx> > >> --- > >> > >> (no changes since v1) > >> > >> drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 16 ++++++++++++++-- > >> drivers/gpu/drm/msm/msm_gpu.c | 2 -- > >> 2 files changed, 14 insertions(+), 4 deletions(-) > >> > >> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c > >> index 4d50110..7ed347c 100644 > >> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c > >> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c > >> @@ -1278,8 +1278,20 @@ static void a6xx_recover(struct msm_gpu *gpu) > >> */ > >> gmu_write(&a6xx_gpu->gmu, REG_A6XX_GMU_GMU_PWR_COL_KEEPALIVE, 0); > >> > >> - gpu->funcs->pm_suspend(gpu); > >> - gpu->funcs->pm_resume(gpu); > >> + /* > >> + * Now drop all the pm_runtime usage count to allow cx gdsc to collapse. > >> + * First drop the usage count from all active submits > >> + */ > >> + for (i = gpu->active_submits; i > 0; i--) > >> + pm_runtime_put(&gpu->pdev->dev); > >> + > >> + /* And the final one from recover worker */ > >> + pm_runtime_put_sync(&gpu->pdev->dev); > >> + > >> + for (i = gpu->active_submits; i > 0; i--) > >> + pm_runtime_get(&gpu->pdev->dev); > >> + > >> + pm_runtime_get_sync(&gpu->pdev->dev); > > In response to v1, Rob suggested pm_runtime_force_suspend/resume(). > > Those seem like they would work to me, too. Why not use them? > Quoting my previous response which I seem to have sent only to Freedreno > list: > > "I believe it is supposed to be used only during system sleep state > transitions. Btw, we don't want pm_runtime_get() calls from elsewhere to > fail by disabling RPM here." The comment about not wanting other runpm calls to fail is valid.. but that is also solveable, ie. by holding a lock around runpm calls. Which I think we need to do anyways, otherwise looping over gpu->active_submits is racey.. I think pm_runtime_force_suspend/resume() is the least-bad option.. or at least I'm not seeing any obvious alternative that is better BR, -R
