[Intel-gfx] [PATCH v2 4/5] drm/i915: Change locking for struct_mutex, v2.

[Chris Wilson]

On Mon, Nov 02, 2015 at 01:57:59PM +0100, Maarten Lankhorst wrote:
> struct_mutex is being locked for every plane in intel_prepare_plane_fb and
> intel_cleanup_plane_fb. This can be optimized by acquiring struct_mutex first
> before calling the atomic helpers. This way the lock only needs to be acquired
> twice in ->atomic_commit(). Once for pinning new framebuffers at the start,
> the second time for unpinning old framebuffer.

A little explanation that you move the locking into the caller would
help clarify the patch.

> @@ -13453,10 +13461,6 @@ intel_prepare_plane_fb(struct drm_plane *plane,
> @@ -13520,7 +13521,6 @@ intel_cleanup_plane_fb(struct drm_plane *plane,

Please document that you now expect both of these functions to be called
with struct_mutex held. Also is there any opportunity to reduce the
struct_mutex lock time?
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre