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| author | Chris Wilson <chris@chris-wilson.co.uk> | 2016-08-05 10:14:21 +0100 |
|---|---|---|
| committer | Chris Wilson <chris@chris-wilson.co.uk> | 2016-08-05 10:54:42 +0100 |
| commit | 9ad3676148511d6af72be6f3638e361fd86e1f7b (patch) | |
| tree | c7e32698c73443ae1de563d0d342e121b910c4c4 /drivers/gpu/drm/i915/i915_gem_tiling.c | |
| parent | e883d73503205d1eaaf049b835bf135b46738f57 (diff) | |
| download | op-kernel-dev-9ad3676148511d6af72be6f3638e361fd86e1f7b.zip op-kernel-dev-9ad3676148511d6af72be6f3638e361fd86e1f7b.tar.gz | |
drm/i915: Remove locking for get_tiling
Since we are not concerned with userspace racing itself with set-tiling
(the order is indeterminant even if we take a lock), then we can safely
read back the single obj->tiling_mode and do the static lookup of
swizzle mode without having to take a lock.
get-tiling is reasonably frequent due to the back-channel passing around
of tiling parameters in DRI2/DRI3.
v2: Make tiling_mode a full unsigned int so that we can trivially use it
with READ_ONCE(). Separating it out into manual control over the flags
field was too noisy for a simple patch. Note that we could use the lower
bits of obj->stride for the tiling mode.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470388464-28458-16-git-send-email-chris@chris-wilson.co.uk
Diffstat (limited to 'drivers/gpu/drm/i915/i915_gem_tiling.c')
| -rw-r--r-- | drivers/gpu/drm/i915/i915_gem_tiling.c | 10 |
1 files changed, 3 insertions, 7 deletions
diff --git a/drivers/gpu/drm/i915/i915_gem_tiling.c b/drivers/gpu/drm/i915/i915_gem_tiling.c index b7f9875..c0e0133 100644 --- a/drivers/gpu/drm/i915/i915_gem_tiling.c +++ b/drivers/gpu/drm/i915/i915_gem_tiling.c @@ -303,10 +303,8 @@ i915_gem_get_tiling(struct drm_device *dev, void *data, if (!obj) return -ENOENT; - mutex_lock(&dev->struct_mutex); - - args->tiling_mode = obj->tiling_mode; - switch (obj->tiling_mode) { + args->tiling_mode = READ_ONCE(obj->tiling_mode); + switch (args->tiling_mode) { case I915_TILING_X: args->swizzle_mode = dev_priv->mm.bit_6_swizzle_x; break; @@ -330,8 +328,6 @@ i915_gem_get_tiling(struct drm_device *dev, void *data, if (args->swizzle_mode == I915_BIT_6_SWIZZLE_9_10_17) args->swizzle_mode = I915_BIT_6_SWIZZLE_9_10; - i915_gem_object_put(obj); - mutex_unlock(&dev->struct_mutex); - + i915_gem_object_put_unlocked(obj); return 0; } |
