[Intel-gfx] [PATCH 2/2] drm/i915: Mark obj->mapping as dirtying the backing storage

[Chris Wilson]

When reviewing some of Tvrtko's usage for i915_gem_object_pin_map(), he
suggested replacing some use of kmap(i915_gem_object_get_dirty_page())
with a plain i915_gem_object_pin_map(). This raised the question of who
should mark the page as dirty (or the mapping case, the object).
We can write simpler, safer code if we mark the entire object as dirty
upon obtaining the obj->mapping. (The counter-argument is that the
caller should be marking the object as dirty itself, or we should be
passing in a direction parameter.)

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Dave Gordon <david.s.gordon at intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
---
 drivers/gpu/drm/i915/i915_gem.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index b37ffea8b458..c0a4e38d6392 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2448,6 +2448,8 @@ void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj)
 		}
 	}
 
+	/* Presume the caller is going to write into the map */
+	obj->dirty = true;
 	return obj->mapping;
 }
 
-- 
2.8.0.rc3