[PATCH 08/10] drm/i915: Replace the complex flushing logic with simple invalidate/flush all

[Chris Wilson <chris@chris-wilson.co.uk>]

Now that we unconditionally flush and invalidate between every batch
buffer, we no longer need the complex logic to decide which domains
require flushing. Remove it and rejoice.

One side-effect is that this also removes the broken wait-on-pending-flip
logic.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_gem_execbuffer.c |  248 ++--------------------------
 1 file changed, 12 insertions(+), 236 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 86aead4..b8d4dc3 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -34,180 +34,6 @@
 #include "intel_drv.h"
 #include <linux/dma_remapping.h>
 
-struct change_domains {
-	uint32_t invalidate_domains;
-	uint32_t flush_domains;
-	uint32_t flush_rings;
-	uint32_t flips;
-};
-
-/*
- * Set the next domain for the specified object. This
- * may not actually perform the necessary flushing/invaliding though,
- * as that may want to be batched with other set_domain operations
- *
- * This is (we hope) the only really tricky part of gem. The goal
- * is fairly simple -- track which caches hold bits of the object
- * and make sure they remain coherent. A few concrete examples may
- * help to explain how it works. For shorthand, we use the notation
- * (read_domains, write_domain), e.g. (CPU, CPU) to indicate the
- * a pair of read and write domain masks.
- *
- * Case 1: the batch buffer
- *
- *	1. Allocated
- *	2. Written by CPU
- *	3. Mapped to GTT
- *	4. Read by GPU
- *	5. Unmapped from GTT
- *	6. Freed
- *
- *	Let's take these a step at a time
- *
- *	1. Allocated
- *		Pages allocated from the kernel may still have
- *		cache contents, so we set them to (CPU, CPU) always.
- *	2. Written by CPU (using pwrite)
- *		The pwrite function calls set_domain (CPU, CPU) and
- *		this function does nothing (as nothing changes)
- *	3. Mapped by GTT
- *		This function asserts that the object is not
- *		currently in any GPU-based read or write domains
- *	4. Read by GPU
- *		i915_gem_execbuffer calls set_domain (COMMAND, 0).
- *		As write_domain is zero, this function adds in the
- *		current read domains (CPU+COMMAND, 0).
- *		flush_domains is set to CPU.
- *		invalidate_domains is set to COMMAND
- *		clflush is run to get data out of the CPU caches
- *		then i915_dev_set_domain calls i915_gem_flush to
- *		emit an MI_FLUSH and drm_agp_chipset_flush
- *	5. Unmapped from GTT
- *		i915_gem_object_unbind calls set_domain (CPU, CPU)
- *		flush_domains and invalidate_domains end up both zero
- *		so no flushing/invalidating happens
- *	6. Freed
- *		yay, done
- *
- * Case 2: The shared render buffer
- *
- *	1. Allocated
- *	2. Mapped to GTT
- *	3. Read/written by GPU
- *	4. set_domain to (CPU,CPU)
- *	5. Read/written by CPU
- *	6. Read/written by GPU
- *
- *	1. Allocated
- *		Same as last example, (CPU, CPU)
- *	2. Mapped to GTT
- *		Nothing changes (assertions find that it is not in the GPU)
- *	3. Read/written by GPU
- *		execbuffer calls set_domain (RENDER, RENDER)
- *		flush_domains gets CPU
- *		invalidate_domains gets GPU
- *		clflush (obj)
- *		MI_FLUSH and drm_agp_chipset_flush
- *	4. set_domain (CPU, CPU)
- *		flush_domains gets GPU
- *		invalidate_domains gets CPU
- *		wait_rendering (obj) to make sure all drawing is complete.
- *		This will include an MI_FLUSH to get the data from GPU
- *		to memory
- *		clflush (obj) to invalidate the CPU cache
- *		Another MI_FLUSH in i915_gem_flush (eliminate this somehow?)
- *	5. Read/written by CPU
- *		cache lines are loaded and dirtied
- *	6. Read written by GPU
- *		Same as last GPU access
- *
- * Case 3: The constant buffer
- *
- *	1. Allocated
- *	2. Written by CPU
- *	3. Read by GPU
- *	4. Updated (written) by CPU again
- *	5. Read by GPU
- *
- *	1. Allocated
- *		(CPU, CPU)
- *	2. Written by CPU
- *		(CPU, CPU)
- *	3. Read by GPU
- *		(CPU+RENDER, 0)
- *		flush_domains = CPU
- *		invalidate_domains = RENDER
- *		clflush (obj)
- *		MI_FLUSH
- *		drm_agp_chipset_flush
- *	4. Updated (written) by CPU again
- *		(CPU, CPU)
- *		flush_domains = 0 (no previous write domain)
- *		invalidate_domains = 0 (no new read domains)
- *	5. Read by GPU
- *		(CPU+RENDER, 0)
- *		flush_domains = CPU
- *		invalidate_domains = RENDER
- *		clflush (obj)
- *		MI_FLUSH
- *		drm_agp_chipset_flush
- */
-static void
-i915_gem_object_set_to_gpu_domain(struct drm_i915_gem_object *obj,
-				  struct intel_ring_buffer *ring,
-				  struct change_domains *cd)
-{
-	uint32_t invalidate_domains = 0, flush_domains = 0;
-
-	/*
-	 * If the object isn't moving to a new write domain,
-	 * let the object stay in multiple read domains
-	 */
-	if (obj->base.pending_write_domain == 0)
-		obj->base.pending_read_domains |= obj->base.read_domains;
-
-	/*
-	 * Flush the current write domain if
-	 * the new read domains don't match. Invalidate
-	 * any read domains which differ from the old
-	 * write domain
-	 */
-	if (obj->base.write_domain &&
-	    (((obj->base.write_domain != obj->base.pending_read_domains ||
-	       obj->ring != ring)) ||
-	     (obj->fenced_gpu_access && !obj->pending_fenced_gpu_access))) {
-		flush_domains |= obj->base.write_domain;
-		invalidate_domains |=
-			obj->base.pending_read_domains & ~obj->base.write_domain;
-	}
-	/*
-	 * Invalidate any read caches which may have
-	 * stale data. That is, any new read domains.
-	 */
-	invalidate_domains |= obj->base.pending_read_domains & ~obj->base.read_domains;
-	if ((flush_domains | invalidate_domains) & I915_GEM_DOMAIN_CPU)
-		i915_gem_clflush_object(obj);
-
-	if (obj->base.pending_write_domain)
-		cd->flips |= atomic_read(&obj->pending_flip);
-
-	/* The actual obj->write_domain will be updated with
-	 * pending_write_domain after we emit the accumulated flush for all
-	 * of our domain changes in execbuffers (which clears objects'
-	 * write_domains).  So if we have a current write domain that we
-	 * aren't changing, set pending_write_domain to that.
-	 */
-	if (flush_domains == 0 && obj->base.pending_write_domain == 0)
-		obj->base.pending_write_domain = obj->base.write_domain;
-
-	cd->invalidate_domains |= invalidate_domains;
-	cd->flush_domains |= flush_domains;
-	if (flush_domains & I915_GEM_GPU_DOMAINS)
-		cd->flush_rings |= intel_ring_flag(obj->ring);
-	if (invalidate_domains & I915_GEM_GPU_DOMAINS)
-		cd->flush_rings |= intel_ring_flag(ring);
-}
-
 struct eb_objects {
 	int and;
 	struct hlist_head buckets[0];
@@ -810,81 +636,31 @@ err:
 	return ret;
 }
 
-static void
-i915_gem_execbuffer_flush(struct drm_device *dev,
-			  uint32_t invalidate_domains,
-			  uint32_t flush_domains)
-{
-	if (flush_domains & I915_GEM_DOMAIN_CPU)
-		intel_gtt_chipset_flush();
-
-	if (flush_domains & I915_GEM_DOMAIN_GTT)
-		wmb();
-}
-
-static int
-i915_gem_execbuffer_wait_for_flips(struct intel_ring_buffer *ring, u32 flips)
-{
-	u32 plane, flip_mask;
-	int ret;
-
-	/* Check for any pending flips. As we only maintain a flip queue depth
-	 * of 1, we can simply insert a WAIT for the next display flip prior
-	 * to executing the batch and avoid stalling the CPU.
-	 */
-
-	for (plane = 0; flips >> plane; plane++) {
-		if (((flips >> plane) & 1) == 0)
-			continue;
-
-		if (plane)
-			flip_mask = MI_WAIT_FOR_PLANE_B_FLIP;
-		else
-			flip_mask = MI_WAIT_FOR_PLANE_A_FLIP;
-
-		ret = intel_ring_begin(ring, 2);
-		if (ret)
-			return ret;
-
-		intel_ring_emit(ring, MI_WAIT_FOR_EVENT | flip_mask);
-		intel_ring_emit(ring, MI_NOOP);
-		intel_ring_advance(ring);
-	}
-
-	return 0;
-}
-
-
 static int
 i915_gem_execbuffer_move_to_gpu(struct intel_ring_buffer *ring,
 				struct list_head *objects)
 {
 	struct drm_i915_gem_object *obj;
-	struct change_domains cd;
+	uint32_t flush_domains = 0;
 	int ret;
 
-	memset(&cd, 0, sizeof(cd));
-	list_for_each_entry(obj, objects, exec_list)
-		i915_gem_object_set_to_gpu_domain(obj, ring, &cd);
-
-	if (cd.invalidate_domains | cd.flush_domains) {
-		i915_gem_execbuffer_flush(ring->dev,
-					  cd.invalidate_domains,
-					  cd.flush_domains);
-	}
-
-	if (cd.flips) {
-		ret = i915_gem_execbuffer_wait_for_flips(ring, cd.flips);
-		if (ret)
-			return ret;
-	}
-
 	list_for_each_entry(obj, objects, exec_list) {
 		ret = i915_gem_object_sync(obj, ring);
 		if (ret)
 			return ret;
+
+		if (obj->base.write_domain & I915_GEM_DOMAIN_CPU)
+			i915_gem_clflush_object(obj);
+
+		flush_domains |= obj->base.write_domain;
 	}
 
+	if (flush_domains & I915_GEM_DOMAIN_CPU)
+		intel_gtt_chipset_flush();
+
+	if (flush_domains & I915_GEM_DOMAIN_GTT)
+		wmb();
+
 	/* Unconditionally invalidate gpu caches and ensure that we do flush
 	 * any residual writes from the previous batch.
 	 */
-- 
1.7.10.4