[Mesa-dev] [PATCH 5/5] radeonsi: use current context for DCC feedback-loop decompress, fixes Elemental

Marek Olšák maraeo at gmail.com
Thu Aug 11 16:16:09 UTC 2016


From: Marek Olšák <marek.olsak at amd.com>

This is just a workaround. The problem is described in the code.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=96541
---
 src/gallium/drivers/radeon/r600_pipe_common.h |  2 +-
 src/gallium/drivers/radeon/r600_texture.c     | 35 ++++++++++++++++++++++-----
 src/gallium/drivers/radeonsi/si_blit.c        | 12 +++------
 src/gallium/drivers/radeonsi/si_descriptors.c |  2 +-
 4 files changed, 35 insertions(+), 16 deletions(-)

diff --git a/src/gallium/drivers/radeon/r600_pipe_common.h b/src/gallium/drivers/radeon/r600_pipe_common.h
index e4002f9..5375044 100644
--- a/src/gallium/drivers/radeon/r600_pipe_common.h
+++ b/src/gallium/drivers/radeon/r600_pipe_common.h
@@ -764,21 +764,21 @@ void vi_separate_dcc_stop_query(struct pipe_context *ctx,
 void vi_separate_dcc_process_and_reset_stats(struct pipe_context *ctx,
 					     struct r600_texture *tex);
 void vi_dcc_clear_level(struct r600_common_context *rctx,
 			struct r600_texture *rtex,
 			unsigned level, unsigned clear_value);
 void evergreen_do_fast_color_clear(struct r600_common_context *rctx,
 				   struct pipe_framebuffer_state *fb,
 				   struct r600_atom *fb_state,
 				   unsigned *buffers, unsigned *dirty_cbufs,
 				   const union pipe_color_union *color);
-bool r600_texture_disable_dcc(struct r600_common_screen *rscreen,
+bool r600_texture_disable_dcc(struct r600_common_context *rctx,
 			      struct r600_texture *rtex);
 void r600_init_screen_texture_functions(struct r600_common_screen *rscreen);
 void r600_init_context_texture_functions(struct r600_common_context *rctx);
 
 /* r600_viewport.c */
 void evergreen_apply_scissor_bug_workaround(struct r600_common_context *rctx,
 					    struct pipe_scissor_state *scissor);
 void r600_set_scissor_enable(struct r600_common_context *rctx, bool enable);
 void r600_update_vs_writes_viewport_index(struct r600_common_context *rctx,
 					  struct tgsi_shader_info *info);
diff --git a/src/gallium/drivers/radeon/r600_texture.c b/src/gallium/drivers/radeon/r600_texture.c
index ddfa135..78dd177 100644
--- a/src/gallium/drivers/radeon/r600_texture.c
+++ b/src/gallium/drivers/radeon/r600_texture.c
@@ -393,34 +393,55 @@ static bool r600_texture_discard_dcc(struct r600_common_screen *rscreen,
 	assert(rtex->dcc_separate_buffer == NULL);
 
 	/* Disable DCC. */
 	rtex->dcc_offset = 0;
 
 	/* Notify all contexts about the change. */
 	r600_dirty_all_framebuffer_states(rscreen);
 	return true;
 }
 
-bool r600_texture_disable_dcc(struct r600_common_screen *rscreen,
+/**
+ * Disable DCC for the texture. (first decompress, then discard metadata).
+ *
+ * Unresolved multi-context synchronization issue:
+ *
+ * If context 1 disables DCC and context 2 has queued commands that write
+ * to the texture via CB with DCC enabled, and the order of operations is
+ * as follows:
+ *   context 2 queues draw calls rendering to the texture, but doesn't flush
+ *   context 1 disables DCC and flushes
+ *   context 1 & 2 reset descriptors and FB state
+ *   context 2 flushes (new compressed tiles written by the draw calls)
+ *   context 1 & 2 read garbage, because DCC is disabled, yet there are
+ *   compressed tiled
+ *
+ * \param rctx  the current context if you have one, or rscreen->aux_context
+ *              if you don't.
+ */
+bool r600_texture_disable_dcc(struct r600_common_context *rctx,
 			      struct r600_texture *rtex)
 {
-	struct r600_common_context *rctx =
-		(struct r600_common_context *)rscreen->aux_context;
+	struct r600_common_screen *rscreen = rctx->screen;
 
 	if (!r600_can_disable_dcc(rtex))
 		return false;
 
+	if (&rctx->b == rscreen->aux_context)
+		pipe_mutex_lock(rscreen->aux_context_lock);
+
 	/* Decompress DCC. */
-	pipe_mutex_lock(rscreen->aux_context_lock);
 	rctx->decompress_dcc(&rctx->b, rtex);
 	rctx->b.flush(&rctx->b, NULL, 0);
-	pipe_mutex_unlock(rscreen->aux_context_lock);
+
+	if (&rctx->b == rscreen->aux_context)
+		pipe_mutex_unlock(rscreen->aux_context_lock);
 
 	return r600_texture_discard_dcc(rscreen, rtex);
 }
 
 static void r600_degrade_tile_mode_to_linear(struct r600_common_context *rctx,
 					     struct r600_texture *rtex,
 					     bool invalidate_storage)
 {
 	struct pipe_screen *screen = rctx->b.screen;
 	struct r600_texture *new_tex;
@@ -485,39 +506,41 @@ static void r600_degrade_tile_mode_to_linear(struct r600_common_context *rctx,
 	r600_dirty_all_framebuffer_states(rctx->screen);
 	p_atomic_inc(&rctx->screen->dirty_tex_descriptor_counter);
 }
 
 static boolean r600_texture_get_handle(struct pipe_screen* screen,
 				       struct pipe_resource *resource,
 				       struct winsys_handle *whandle,
                                        unsigned usage)
 {
 	struct r600_common_screen *rscreen = (struct r600_common_screen*)screen;
+	struct r600_common_context *aux_context =
+		(struct r600_common_context*)rscreen->aux_context;
 	struct r600_resource *res = (struct r600_resource*)resource;
 	struct r600_texture *rtex = (struct r600_texture*)resource;
 	struct radeon_bo_metadata metadata;
 	bool update_metadata = false;
 
 	/* This is not supported now, but it might be required for OpenCL
 	 * interop in the future.
 	 */
 	if (resource->target != PIPE_BUFFER &&
 	    (resource->nr_samples > 1 || rtex->is_depth))
 		return false;
 
 	if (resource->target != PIPE_BUFFER) {
 		/* Since shader image stores don't support DCC on VI,
 		 * disable it for external clients that want write
 		 * access.
 		 */
 		if (usage & PIPE_HANDLE_USAGE_WRITE && rtex->dcc_offset) {
-			if (r600_texture_disable_dcc(rscreen, rtex))
+			if (r600_texture_disable_dcc(aux_context, rtex))
 				update_metadata = true;
 		}
 
 		if (!(usage & PIPE_HANDLE_USAGE_EXPLICIT_FLUSH) &&
 		    rtex->cmask.size) {
 			/* Eliminate fast clear (both CMASK and DCC) */
 			r600_eliminate_fast_color_clear(rscreen, rtex);
 
 			/* Disable CMASK if flush_resource isn't going
 			 * to be called.
diff --git a/src/gallium/drivers/radeonsi/si_blit.c b/src/gallium/drivers/radeonsi/si_blit.c
index f4bff6b..3cfd011 100644
--- a/src/gallium/drivers/radeonsi/si_blit.c
+++ b/src/gallium/drivers/radeonsi/si_blit.c
@@ -550,24 +550,22 @@ static void si_check_render_feedback_textures(struct si_context *sctx,
 			surf = (struct r600_surface*)sctx->framebuffer.state.cbufs[j];
 
 			if (tex == (struct r600_texture*)surf->base.texture &&
 			    surf->base.u.tex.level >= view->u.tex.first_level &&
 			    surf->base.u.tex.level <= view->u.tex.last_level &&
 			    surf->base.u.tex.first_layer <= view->u.tex.last_layer &&
 			    surf->base.u.tex.last_layer >= view->u.tex.first_layer)
 				render_feedback = true;
 		}
 
-		if (render_feedback) {
-			struct si_screen *screen = sctx->screen;
-			r600_texture_disable_dcc(&screen->b, tex);
-		}
+		if (render_feedback)
+			r600_texture_disable_dcc(&sctx->b, tex);
 	}
 }
 
 static void si_check_render_feedback_images(struct si_context *sctx,
                                             struct si_images_info *images)
 {
 	uint32_t mask = images->enabled_mask;
 
 	while (mask) {
 		const struct pipe_image_view *view;
@@ -592,24 +590,22 @@ static void si_check_render_feedback_images(struct si_context *sctx,
 
 			surf = (struct r600_surface*)sctx->framebuffer.state.cbufs[j];
 
 			if (tex == (struct r600_texture*)surf->base.texture &&
 			    surf->base.u.tex.level == view->u.tex.level &&
 			    surf->base.u.tex.first_layer <= view->u.tex.last_layer &&
 			    surf->base.u.tex.last_layer >= view->u.tex.first_layer)
 				render_feedback = true;
 		}
 
-		if (render_feedback) {
-			struct si_screen *screen = sctx->screen;
-			r600_texture_disable_dcc(&screen->b, tex);
-		}
+		if (render_feedback)
+			r600_texture_disable_dcc(&sctx->b, tex);
 	}
 }
 
 static void si_check_render_feedback(struct si_context *sctx)
 {
 
 	if (!sctx->need_check_render_feedback)
 		return;
 
 	for (int i = 0; i < SI_NUM_SHADERS; ++i) {
diff --git a/src/gallium/drivers/radeonsi/si_descriptors.c b/src/gallium/drivers/radeonsi/si_descriptors.c
index 7600671..1d04a9c 100644
--- a/src/gallium/drivers/radeonsi/si_descriptors.c
+++ b/src/gallium/drivers/radeonsi/si_descriptors.c
@@ -656,21 +656,21 @@ static void si_set_shader_image(struct si_context *ctx,
 
 		assert(!tex->is_depth);
 		assert(tex->fmask.size == 0);
 
 		if (uses_dcc &&
 		    view->access & PIPE_IMAGE_ACCESS_WRITE) {
 			/* If DCC can't be disabled, at least decompress it.
 			 * The decompression is relatively cheap if the surface
 			 * has been decompressed already.
 			 */
-			if (r600_texture_disable_dcc(&screen->b, tex))
+			if (r600_texture_disable_dcc(&ctx->b, tex))
 				uses_dcc = false;
 			else
 				ctx->b.decompress_dcc(&ctx->b.b, tex);
 		}
 
 		if (is_compressed_colortex(tex)) {
 			images->compressed_colortex_mask |= 1 << slot;
 		} else {
 			images->compressed_colortex_mask &= ~(1 << slot);
 		}
-- 
2.7.4



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