The individual bits inside obj->frontbuffer_bits are protected by each
plane->mutex, but the whole bitfield may be accessed by multiple KMS
operations simultaneously and so the RMW need to be under atomics.
However, for updating the single field we do not need to mandate that it
be under the struct_mutex, one more step towards its removal as the de
facto BKL.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
---
drivers/gpu/drm/i915/i915_debugfs.c | 6 ++++--
drivers/gpu/drm/i915/i915_drv.h | 4 +---
drivers/gpu/drm/i915/i915_gem.c | 18 +++++++++++-------
drivers/gpu/drm/i915/intel_display.c | 18 ++++++------------
drivers/gpu/drm/i915/intel_drv.h | 20 ++++++++++++++------
drivers/gpu/drm/i915/intel_frontbuffer.c | 23 +++++++++--------------
6 files changed, 45 insertions(+), 44 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index fcfa9ca6b50a..10a346237795 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -138,6 +138,7 @@ describe_obj(struct seq_file *m, struct drm_i915_gem_object *obj)
struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
struct intel_engine_cs *engine;
struct i915_vma *vma;
+ unsigned int frontbuffer_bits;
int pin_count = 0;
enum intel_engine_id id;
@@ -204,8 +205,9 @@ describe_obj(struct seq_file *m, struct drm_i915_gem_object *obj)
if (engine)
seq_printf(m, " (%s)", engine->name);
- if (obj->frontbuffer_bits)
- seq_printf(m, " (frontbuffer: 0x%03x)", obj->frontbuffer_bits);
+ frontbuffer_bits = atomic_read(&obj->frontbuffer_bits);
+ if (frontbuffer_bits)
+ seq_printf(m, " (frontbuffer: 0x%03x)", frontbuffer_bits);
}
static int i915_gem_object_list_info(struct seq_file *m, void *data)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index a24d31e3e014..b6b9a1f78238 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2127,8 +2127,6 @@ struct drm_i915_gem_object_ops {
*/
#define INTEL_MAX_SPRITE_BITS_PER_PIPE 5
#define INTEL_FRONTBUFFER_BITS_PER_PIPE 8
-#define INTEL_FRONTBUFFER_BITS \
- (INTEL_FRONTBUFFER_BITS_PER_PIPE * I915_MAX_PIPES)
#define INTEL_FRONTBUFFER_PRIMARY(pipe) \
(1 << (INTEL_FRONTBUFFER_BITS_PER_PIPE * (pipe)))
#define INTEL_FRONTBUFFER_CURSOR(pipe) \
@@ -2216,7 +2214,7 @@ struct drm_i915_gem_object {
unsigned int cache_level:3;
unsigned int cache_dirty:1;
- unsigned int frontbuffer_bits:INTEL_FRONTBUFFER_BITS;
+ atomic_t frontbuffer_bits;
unsigned int has_wc_mmap;
/** Count of VMA actually bound by this object */
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 7db0808f6961..bc5bc5ccdde0 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4031,7 +4031,7 @@ void i915_gem_free_object(struct drm_gem_object *gem_obj)
if (obj->stolen)
i915_gem_object_unpin_pages(obj);
- WARN_ON(obj->frontbuffer_bits);
+ WARN_ON(atomic_read(&obj->frontbuffer_bits));
if (obj->pages && obj->madv == I915_MADV_WILLNEED &&
dev_priv->quirks & QUIRK_PIN_SWIZZLED_PAGES &&
@@ -4549,16 +4549,20 @@ void i915_gem_track_fb(struct drm_i915_gem_object *old,
struct drm_i915_gem_object *new,
unsigned frontbuffer_bits)
{
+ /* Control of individual bits within the bitfield are guarded by
+ * the owning plane->mutex, i.e. we can never see concurrent
+ * manipulation of individual bits. But since the bitfield as a whole
+ * is updated using RMW, we need to use atomics in order to update
+ * the bits.
+ */
if (old) {
- WARN_ON(!mutex_is_locked(&old->base.dev->struct_mutex));
- WARN_ON(!(old->frontbuffer_bits & frontbuffer_bits));
- old->frontbuffer_bits &= ~frontbuffer_bits;
+ WARN_ON(!(atomic_read(&old->frontbuffer_bits) & frontbuffer_bits));
+ atomic_andnot(frontbuffer_bits, &old->frontbuffer_bits);
}
if (new) {
- WARN_ON(!mutex_is_locked(&new->base.dev->struct_mutex));
- WARN_ON(new->frontbuffer_bits & frontbuffer_bits);
- new->frontbuffer_bits |= frontbuffer_bits;
+ WARN_ON(atomic_read(&new->frontbuffer_bits) & frontbuffer_bits);
+ atomic_or(frontbuffer_bits, &new->frontbuffer_bits);
}
}
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index ed2069c56036..1c70f68328b4 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2600,7 +2600,8 @@ valid_fb:
primary->fb = primary->state->fb = fb;
primary->crtc = primary->state->crtc = &intel_crtc->base;
intel_crtc->base.state->plane_mask |= (1 << drm_plane_index(primary));
- obj->frontbuffer_bits |= to_intel_plane(primary)->frontbuffer_bit;
+ atomic_or(to_intel_plane(primary)->frontbuffer_bit,
+ &obj->frontbuffer_bits);
}
static void i9xx_update_primary_plane(struct drm_plane *primary,
@@ -13807,19 +13808,12 @@ static void intel_atomic_track_fbs(struct drm_atomic_state *state)
{
struct drm_plane_state *old_plane_state;
struct drm_plane *plane;
- struct drm_i915_gem_object *obj, *old_obj;
- struct intel_plane *intel_plane;
int i;
- mutex_lock(&state->dev->struct_mutex);
- for_each_plane_in_state(state, plane, old_plane_state, i) {
- obj = intel_fb_obj(plane->state->fb);
- old_obj = intel_fb_obj(old_plane_state->fb);
- intel_plane = to_intel_plane(plane);
-
- i915_gem_track_fb(old_obj, obj, intel_plane->frontbuffer_bit);
- }
- mutex_unlock(&state->dev->struct_mutex);
+ for_each_plane_in_state(state, plane, old_plane_state, i)
+ i915_gem_track_fb(intel_fb_obj(old_plane_state->fb),
+ intel_fb_obj(plane->state->fb),
+ to_intel_plane(plane)->frontbuffer_bit);
}
/**
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 01056ce8d461..5294039cf238 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -1147,27 +1147,35 @@ unsigned int intel_fb_align_height(struct drm_device *dev,
uint64_t fb_format_modifier);
void __intel_fb_obj_invalidate(struct drm_i915_gem_object *obj,
- enum fb_op_origin origin);
+ enum fb_op_origin origin,
+ unsigned int frontbuffer_bits);
static inline void intel_fb_obj_invalidate(struct drm_i915_gem_object *obj,
enum fb_op_origin origin)
{
- if (!obj->frontbuffer_bits)
+ unsigned int frontbuffer_bits;
+
+ frontbuffer_bits = atomic_read(&obj->frontbuffer_bits);
+ if (!frontbuffer_bits)
return;
- __intel_fb_obj_invalidate(obj, origin);
+ __intel_fb_obj_invalidate(obj, origin, frontbuffer_bits);
}
void __intel_fb_obj_flush(struct drm_i915_gem_object *obj,
bool retire,
- enum fb_op_origin origin);
+ enum fb_op_origin origin,
+ unsigned int frontbuffer_tibst);
static inline void intel_fb_obj_flush(struct drm_i915_gem_object *obj,
bool retire,
enum fb_op_origin origin)
{
- if (!obj->frontbuffer_bits)
+ unsigned int frontbuffer_bits;
+
+ frontbuffer_bits = atomic_read(&obj->frontbuffer_bits);
+ if (!frontbuffer_bits)
return;
- __intel_fb_obj_flush(obj, retire, origin);
+ __intel_fb_obj_flush(obj, retire, origin, frontbuffer_bits);
}
u32 intel_fb_stride_alignment(const struct drm_i915_private *dev_priv,
diff --git a/drivers/gpu/drm/i915/intel_frontbuffer.c b/drivers/gpu/drm/i915/intel_frontbuffer.c
index a38ccfe4894a..636324da21c2 100644
--- a/drivers/gpu/drm/i915/intel_frontbuffer.c
+++ b/drivers/gpu/drm/i915/intel_frontbuffer.c
@@ -77,23 +77,22 @@
* scheduled.
*/
void __intel_fb_obj_invalidate(struct drm_i915_gem_object *obj,
- enum fb_op_origin origin)
+ enum fb_op_origin origin,
+ unsigned int frontbuffer_bits)
{
struct drm_device *dev = obj->base.dev;
struct drm_i915_private *dev_priv = to_i915(dev);
- WARN_ON(!mutex_is_locked(&dev->struct_mutex));
-
if (origin == ORIGIN_CS) {
spin_lock(&dev_priv->fb_tracking.lock);
- dev_priv->fb_tracking.busy_bits |= obj->frontbuffer_bits;
- dev_priv->fb_tracking.flip_bits &= ~obj->frontbuffer_bits;
+ dev_priv->fb_tracking.busy_bits |= frontbuffer_bits;
+ dev_priv->fb_tracking.flip_bits &= ~frontbuffer_bits;
spin_unlock(&dev_priv->fb_tracking.lock);
}
- intel_psr_invalidate(dev, obj->frontbuffer_bits);
- intel_edp_drrs_invalidate(dev, obj->frontbuffer_bits);
- intel_fbc_invalidate(dev_priv, obj->frontbuffer_bits, origin);
+ intel_psr_invalidate(dev, frontbuffer_bits);
+ intel_edp_drrs_invalidate(dev, frontbuffer_bits);
+ intel_fbc_invalidate(dev_priv, frontbuffer_bits, origin);
}
/**
@@ -139,15 +138,11 @@ static void intel_frontbuffer_flush(struct drm_device *dev,
*/
void __intel_fb_obj_flush(struct drm_i915_gem_object *obj,
bool retire,
- enum fb_op_origin origin)
+ enum fb_op_origin origin,
+ unsigned int frontbuffer_bits)
{
struct drm_device *dev = obj->base.dev;
struct drm_i915_private *dev_priv = to_i915(dev);
- unsigned frontbuffer_bits;
-
- WARN_ON(!mutex_is_locked(&dev->struct_mutex));
-
- frontbuffer_bits = obj->frontbuffer_bits;
if (retire) {
spin_lock(&dev_priv->fb_tracking.lock);
--
2.8.1
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