From 5b364bec5cbfd6c23505952a40150b053ec551d1 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Tue, 30 Jan 2018 16:44:57 +0000 Subject: [PATCH] drm/i915: Flush ggtt writes through the old fenced vma before changing fences This is a precautionary measure as I have no evidence to suggest we've hit a bug here (I was hoping this might explain gdg's odd behaviour, but alas), but given that we have a function to flush the ggtt writes it seems prudent to use it prior to changing the fence register. Due to the intrinsic nature of the GTT often operating as an independent mmio path, we should not just rely on the write to the fence acting as a full flush for GTT writes. Signed-off-by: Chris Wilson Cc: Joonas Lahtinen Reviewed-by: Joonas Lahtinen Link: https://patchwork.freedesktop.org/patch/msgid/20180130164457.14037-1-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/i915_gem_fence_reg.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem_fence_reg.c b/drivers/gpu/drm/i915/i915_gem_fence_reg.c index 012250f..b8338d7 100644 --- a/drivers/gpu/drm/i915/i915_gem_fence_reg.c +++ b/drivers/gpu/drm/i915/i915_gem_fence_reg.c @@ -230,10 +230,14 @@ static int fence_update(struct drm_i915_fence_reg *fence, } if (fence->vma) { - ret = i915_gem_active_retire(&fence->vma->last_fence, - &fence->vma->obj->base.dev->struct_mutex); + struct i915_vma *old = fence->vma; + + ret = i915_gem_active_retire(&old->last_fence, + &old->obj->base.dev->struct_mutex); if (ret) return ret; + + i915_vma_flush_writes(old); } if (fence->vma && fence->vma != vma) { -- 2.7.4