[Intel-gfx] [PATCH 3/3] drm/i915: mark GEM objects as dirty when written by the CPU

[Dave Gordon]

This patch covers a couple more places where a GEM object is (or may be)
modified by means of CPU writes, and should therefore be marked dirty to
ensure that the changes are not lost in the evenof of the object is
evicted under memory pressure.

It may be possible to optimise these paths later, by marking only
specific pages of the object as dirty (for objects backed by shmfs
pages); but for now let's ensure correctness by dirtying the whole
object.

Signed-off-by: Dave Gordon <david.s.gordon at intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_gem.c        | 4 +++-
 drivers/gpu/drm/i915/i915_gem_dmabuf.c | 2 ++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 12f68f4..36b9539 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -937,7 +937,6 @@ i915_gem_shmem_pwrite(struct drm_device *dev,
 	i915_gem_object_pin_pages(obj);
 
 	offset = args->offset;
-	obj->dirty = 1;
 
 	for_each_sg_page(obj->pages->sgl, &sg_iter, obj->pages->nents,
 			 offset >> PAGE_SHIFT) {
@@ -1074,6 +1073,9 @@ i915_gem_pwrite_ioctl(struct drm_device *dev, void *data,
 		goto out;
 	}
 
+	/* Object backing store will be out of date hereafter */
+	obj->dirty = 1;
+
 	trace_i915_gem_object_pwrite(obj, args->offset, args->size);
 
 	ret = -EFAULT;
diff --git a/drivers/gpu/drm/i915/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
index e9c2bfd..49a74c6 100644
--- a/drivers/gpu/drm/i915/i915_gem_dmabuf.c
+++ b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
@@ -208,6 +208,8 @@ static int i915_gem_begin_cpu_access(struct dma_buf *dma_buf, size_t start, size
 		return ret;
 
 	ret = i915_gem_object_set_to_cpu_domain(obj, write);
+	if (write)
+		obj->dirty = 1;
 	mutex_unlock(&dev->struct_mutex);
 	return ret;
 }
-- 
1.9.1