Messages in this thread | | | Date | Thu, 16 Jun 2022 11:27:39 +0300 | Subject | Re: [PATCH] drm/msm: Fix fence rollover issue | From | Dmitry Baryshkov <> |
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On 15/06/2022 19:24, Rob Clark wrote: > From: Rob Clark <robdclark@chromium.org> > > And while we are at it, let's start the fence counter close to the > rollover point so that if issues slip in, they are more obvious. > > Signed-off-by: Rob Clark <robdclark@chromium.org>
Should it also have
Fixes: fde5de6cb461 ("drm/msm: move fence code to it's own file")
Or maybe
Fixes: 5f3aee4ceb5b ("drm/msm: Handle fence rollover")
Otherwise:
Reviewed: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> --- > drivers/gpu/drm/msm/msm_fence.c | 13 +++++++++++-- > 1 file changed, 11 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/msm/msm_fence.c b/drivers/gpu/drm/msm/msm_fence.c > index 3df255402a33..a35a6746c7cd 100644 > --- a/drivers/gpu/drm/msm/msm_fence.c > +++ b/drivers/gpu/drm/msm/msm_fence.c > @@ -28,6 +28,14 @@ msm_fence_context_alloc(struct drm_device *dev, volatile uint32_t *fenceptr, > fctx->fenceptr = fenceptr; > spin_lock_init(&fctx->spinlock); > > + /* > + * Start out close to the 32b fence rollover point, so we can > + * catch bugs with fence comparisons. > + */ > + fctx->last_fence = 0xffffff00; > + fctx->completed_fence = fctx->last_fence; > + *fctx->fenceptr = fctx->last_fence;
This looks like a debugging hack. But probably it's fine to have it, as it wouldn't cause any side effects.
> + > return fctx; > } > > @@ -46,11 +54,12 @@ bool msm_fence_completed(struct msm_fence_context *fctx, uint32_t fence) > (int32_t)(*fctx->fenceptr - fence) >= 0; > } > > -/* called from workqueue */ > +/* called from irq handler */ > void msm_update_fence(struct msm_fence_context *fctx, uint32_t fence) > { > spin_lock(&fctx->spinlock); > - fctx->completed_fence = max(fence, fctx->completed_fence); > + if (fence_after(fence, fctx->completed_fence)) > + fctx->completed_fence = fence; > spin_unlock(&fctx->spinlock); > } >
-- With best wishes Dmitry
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