Commit 5d82e3e6 authored by Chris Wilson's avatar Chris Wilson Committed by Daniel Vetter
Browse files

drm/i915: Clarify the semantics of tiling_changed

Rename obj->tiling_changed to obj->fence_dirty so that it is clear that
it flags when the parameters for an active fence (including the
no-fence) register are changed.

Also, do not set this flag when the object does not have a fence
register allocated currently and the gpu does not depend upon the
unfence. This case works exactly like when a tiled object lost its
fence and hence does not need additional handling for the tiling
change in the code.

v2: Use fence_dirty to better express what the flag tracks and add a few
more details to the comments to serve as a reminder of how the GPU also
uses the unfenced register slot.
Signed-off-by: default avatarChris Wilson <>
[danvet: Add some bikeshed to the commit message about the stricter
use of fence_dirty.]
Signed-off-by: default avatarDaniel Vetter <>
parent 38de45c5
......@@ -869,7 +869,14 @@ struct drm_i915_gem_object {
* Current tiling mode for the object.
unsigned int tiling_mode:2;
unsigned int tiling_changed:1;
* 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
* slot that the object occupies whilst it executes a fenced
* command (such as BLT on gen2/3), as a "fence".
unsigned int fence_dirty:1;
/** How many users have pinned this object in GTT space. The following
* users can each hold at most one reference: pwrite/pread, pin_ioctl
......@@ -66,7 +66,7 @@ static inline void i915_gem_object_fence_lost(struct drm_i915_gem_object *obj)
/* As we do not have an associated fence register, we will force
* a tiling change if we ever need to acquire one.
obj->tiling_changed = false;
obj->fence_dirty = false;
obj->fence_reg = I915_FENCE_REG_NONE;
......@@ -2459,7 +2459,7 @@ i915_gem_object_get_fence(struct drm_i915_gem_object *obj)
/* Have we updated the tiling parameters upon the object and so
* will need to serialise the write to the associated fence register?
if (obj->tiling_changed) {
if (obj->fence_dirty) {
ret = i915_gem_object_flush_fence(obj);
if (ret)
return ret;
......@@ -2468,7 +2468,7 @@ i915_gem_object_get_fence(struct drm_i915_gem_object *obj)
/* Just update our place in the LRU if our fence is getting reused. */
if (obj->fence_reg != I915_FENCE_REG_NONE) {
reg = &dev_priv->fence_regs[obj->fence_reg];
if (!obj->tiling_changed) {
if (!obj->fence_dirty) {
return 0;
......@@ -2491,7 +2491,7 @@ i915_gem_object_get_fence(struct drm_i915_gem_object *obj)
return 0;
i915_gem_object_update_fence(obj, reg, enable);
obj->tiling_changed = false;
obj->fence_dirty = false;
return 0;
......@@ -355,6 +355,11 @@ i915_gem_set_tiling(struct drm_device *dev, void *data,
* no longer meets the alignment restrictions for its new
* tiling mode. Otherwise we can just leave it alone, but
* need to ensure that any fence register is cleared.
* After updating the tiling parameters, we then flag whether
* we need to update an associated fence register. Note this
* has to also include the unfenced register the GPU uses
* whilst executing a fenced command for an untiled object.
......@@ -374,7 +379,10 @@ i915_gem_set_tiling(struct drm_device *dev, void *data,
if (ret == 0) {
obj->tiling_changed = true;
obj->fence_dirty =
obj->fenced_gpu_access ||
obj->fence_reg != I915_FENCE_REG_NONE;
obj->tiling_mode = args->tiling_mode;
obj->stride = args->stride;
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