[Mesa-stable] [PATCH] i965: Disable regular fast-clears (CCS_D) on gen9+

[Jason Ekstrand]

This partially reverts commit 3e57e9494c2279580ad6a83ab8c065d01e7e634e
which caused a bunch of GPU hangs on several Source titles.  To date, we
have no clue why these hangs are actually happening.  This undoes the
final effect of 3e57e9494c227 and gets us back to not hanging.  Tested
with Team Fortress 2.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=102435
Fixes: 3e57e9494c2279580ad6a83ab8c065d01e7e634e
Cc: mesa-stable at lists.freedesktop.org
---
 src/mesa/drivers/dri/i965/brw_meta_util.c     | 11 ++++++
 src/mesa/drivers/dri/i965/intel_mipmap_tree.c | 55 +++++++++++++++------------
 2 files changed, 42 insertions(+), 24 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_meta_util.c b/src/mesa/drivers/dri/i965/brw_meta_util.c
index d292f5a..ba92168 100644
--- a/src/mesa/drivers/dri/i965/brw_meta_util.c
+++ b/src/mesa/drivers/dri/i965/brw_meta_util.c
@@ -293,6 +293,17 @@ brw_is_color_fast_clear_compatible(struct brw_context *brw,
        brw->mesa_to_isl_render_format[mt->format])
       return false;
 
+   /* Gen9 doesn't support fast clear on single-sampled SRGB buffers. When
+    * GL_FRAMEBUFFER_SRGB is enabled any color renderbuffers will be
+    * resolved in intel_update_state. In that case it's pointless to do a
+    * fast clear because it's very likely to be immediately resolved.
+    */
+   if (devinfo->gen >= 9 &&
+       mt->surf.samples == 1 &&
+       ctx->Color.sRGBEnabled &&
+       _mesa_get_srgb_format_linear(mt->format) != mt->format)
+      return false;
+
    const mesa_format format = _mesa_get_render_format(ctx, mt->format);
    if (_mesa_is_format_integer_color(format)) {
       if (devinfo->gen >= 8) {
diff --git a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
index b87d356..041abb2 100644
--- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
+++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
@@ -207,7 +207,13 @@ intel_miptree_supports_ccs(struct brw_context *brw,
    if (!brw->mesa_format_supports_render[mt->format])
       return false;
 
-   return true;
+   if (devinfo->gen >= 9) {
+      mesa_format linear_format = _mesa_get_srgb_format_linear(mt->format);
+      const enum isl_format isl_format =
+         brw_isl_format_for_mesa_format(linear_format);
+      return isl_format_supports_ccs_e(&brw->screen->devinfo, isl_format);
+   } else
+      return true;
 }
 
 static bool
@@ -284,13 +290,12 @@ intel_miptree_supports_ccs_e(struct brw_context *brw,
    if (!intel_miptree_supports_ccs(brw, mt))
       return false;
 
-   /* Many window system buffers are sRGB even if they are never rendered as
-    * sRGB.  For those, we want CCS_E for when sRGBEncode is false.  When the
-    * surface is used as sRGB, we fall back to CCS_D.
+   /* Fast clear can be also used to clear srgb surfaces by using equivalent
+    * linear format. This trick, however, can't be extended to be used with
+    * lossless compression and therefore a check is needed to see if the format
+    * really is linear.
     */
-   mesa_format linear_format = _mesa_get_srgb_format_linear(mt->format);
-   enum isl_format isl_format = brw_isl_format_for_mesa_format(linear_format);
-   return isl_format_supports_ccs_e(&brw->screen->devinfo, isl_format);
+   return _mesa_get_srgb_format_linear(mt->format) == mt->format;
 }
 
 /**
@@ -2681,27 +2686,29 @@ intel_miptree_render_aux_usage(struct brw_context *brw,
       return ISL_AUX_USAGE_MCS;
 
    case ISL_AUX_USAGE_CCS_D:
-      return mt->mcs_buf ? ISL_AUX_USAGE_CCS_D : ISL_AUX_USAGE_NONE;
-
-   case ISL_AUX_USAGE_CCS_E: {
-      /* If the format supports CCS_E and is compatible with the miptree,
-       * then we can use it.
+      /* If FRAMEBUFFER_SRGB is used on Gen9+ then we need to resolve any of
+       * the single-sampled color renderbuffers because the CCS buffer isn't
+       * supported for SRGB formats. This only matters if FRAMEBUFFER_SRGB is
+       * enabled because otherwise the surface state will be programmed with
+       * the linear equivalent format anyway.
        */
-      if (format_ccs_e_compat_with_miptree(&brw->screen->devinfo,
-                                           mt, render_format))
-         return ISL_AUX_USAGE_CCS_E;
-
-      /* Otherwise, we have to fall back to CCS_D */
+      if (isl_format_is_srgb(render_format) &&
+          _mesa_get_srgb_format_linear(mt->format) != mt->format) {
+         return ISL_AUX_USAGE_NONE;
+      } else if (!mt->mcs_buf) {
+         return ISL_AUX_USAGE_NONE;
+      } else {
+         return ISL_AUX_USAGE_CCS_D;
+      }
 
-      /* gen9 hardware technically supports non-0/1 clear colors with sRGB
-       * formats.  However, there are issues with blending where it doesn't
-       * properly apply the sRGB curve to the clear color when blending.
+   case ISL_AUX_USAGE_CCS_E: {
+      /* Lossless compression is not supported for SRGB formats, it
+       * should be impossible to get here with such surfaces.
        */
-      if (blend_enabled && isl_format_is_srgb(render_format) &&
-          !isl_color_value_is_zero_one(mt->fast_clear_color, render_format))
-         return ISL_AUX_USAGE_NONE;
+      assert(!isl_format_is_srgb(render_format) ||
+             _mesa_get_srgb_format_linear(mt->format) == mt->format);
 
-      return ISL_AUX_USAGE_CCS_D;
+      return ISL_AUX_USAGE_CCS_E;
    }
 
    default:
-- 
2.5.0.400.gff86faf