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
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 31a614f..f18d876 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2183,10 +2183,6 @@
unsigned int madv:2;
/**
- * Current tiling mode for the object.
- */
- unsigned int tiling_mode:2;
- /**
* Whether the tiling parameters for the currently associated fence
* register have changed. Note that for the purposes of tracking
* tiling changes we also treat the unfenced register, the register
@@ -2218,6 +2214,14 @@
atomic_t frontbuffer_bits;
+ /**
+ * Current tiling mode for the object.
+ */
+ unsigned int tiling_mode;
+
+ /** Current tiling stride for the object, if it's tiled. */
+ uint32_t stride;
+
unsigned int has_wc_mmap;
/** Count of VMA actually bound by this object */
unsigned int bind_count;
@@ -2245,9 +2249,6 @@
struct i915_gem_active last_write;
struct i915_gem_active last_fence;
- /** Current tiling stride for the object, if it's tiled. */
- uint32_t stride;
-
/** References from framebuffers, locks out tiling changes. */
unsigned long framebuffer_references;