On Fri, Dec 22, 2023 at 11:58 AM Akhil P Oommen <quic_akhi...@quicinc.com> wrote: > > On Mon, Dec 18, 2023 at 07:59:24AM -0800, Rob Clark wrote: > > > > From: Rob Clark <robdcl...@chromium.org> > > > > a6xx_recover() is relying on the gpu lock to serialize against incoming > > submits doing a runpm get, as it tries to temporarily balance out the > > runpm gets with puts in order to power off the GPU. Unfortunately this > > gets worse when we (in a later patch) will move the runpm get out of the > > scheduler thread/work to move it out of the fence signaling path. > > > > Instead we can just simplify the whole thing by using force_suspend() / > > force_resume() instead of trying to be clever. > > At some places, we take a pm_runtime vote and access the gpu > registers assuming it will be powered until we drop the vote. > a6xx_get_timestamp() > is an example. If we do a force suspend, it may cause bus errors from > those threads. Now you have to serialize every place we do runtime_get/put > with a > mutex. Or is there a better way to handle the 'later patch' you > mentioned?
So I was running into issues, when I started adding an igt test to stress test recovery vs multi-threaded submit, with cxpd not always suspending and getting "cx gdsc did not collapse", which may be related. I was considering using force_suspend() on the gmu and cxpd if gpu->hang==true, I'm not sure. I ran out of time to play with this when I was in the office. The issue the 'later patch' is trying to deal with is getting memory allocations out of the "fence signaling path", ie. out from the drm/sched kthread/worker. One way to do that, without dragging all of runpm/device-link/etc into it is to do the runpm get in the submit ioctl before enqueuing the job to the scheduler. But then we can hold a lock to protect against racing with recovery. BR, -R > -Akhil. > > > > > Reported-by: David Heidelberg <david.heidelb...@collabora.com> > > Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/10272 > > Fixes: abe2023b4cea ("drm/msm/gpu: Push gpu lock down past runpm") > > Signed-off-by: Rob Clark <robdcl...@chromium.org> > > --- > > drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 12 ++---------- > > 1 file changed, 2 insertions(+), 10 deletions(-) > > > > diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c > > b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c > > index 268737e59131..a5660d63535b 100644 > > --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c > > +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c > > @@ -1244,12 +1244,7 @@ static void a6xx_recover(struct msm_gpu *gpu) > > dev_pm_genpd_add_notifier(gmu->cxpd, &gmu->pd_nb); > > dev_pm_genpd_synced_poweroff(gmu->cxpd); > > > > - /* Drop the rpm refcount from active submits */ > > - if (active_submits) > > - pm_runtime_put(&gpu->pdev->dev); > > - > > - /* And the final one from recover worker */ > > - pm_runtime_put_sync(&gpu->pdev->dev); > > + pm_runtime_force_suspend(&gpu->pdev->dev); > > > > if (!wait_for_completion_timeout(&gmu->pd_gate, > > msecs_to_jiffies(1000))) > > DRM_DEV_ERROR(&gpu->pdev->dev, "cx gdsc didn't collapse\n"); > > @@ -1258,10 +1253,7 @@ static void a6xx_recover(struct msm_gpu *gpu) > > > > pm_runtime_use_autosuspend(&gpu->pdev->dev); > > > > - if (active_submits) > > - pm_runtime_get(&gpu->pdev->dev); > > - > > - pm_runtime_get_sync(&gpu->pdev->dev); > > + pm_runtime_force_resume(&gpu->pdev->dev); > > > > gpu->active_submits = active_submits; > > mutex_unlock(&gpu->active_lock); > > -- > > 2.43.0 > >
