i965/skl: Add fast color clear infrastructure

Patch was originally called:
i965/skl: Enable fast color clears on SKL

Skylake introduces some differences in the way that fast clears are programmed
and in the restrictions for using fast clears. Since some of these are
non-obvious, and fast clears are currently disabled globally, we can enable the
simple stuff here and leave the weirder stuff and separately reviewable work.

Based on a patch originally from Kristian.

Note that within this patch the change in scaling factors could be achieved with
this hunk instead. I've opted to keep things more like how the docs describe it
however.
   --- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
   +++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
   @@ -150,9 +150,13 @@ intel_get_non_msrt_mcs_alignment(struct brw_context *brw,
          /* In release builds, fall through */
       case I915_TILING_Y:
          *width_px = 32 / mt->cpp;
   -      *height = 4;
   +      if (brw->gen >= 9)
   +         *height = 2;
   +      else
   +         *height = 4;

v2: Add braces for the multiline (Matt + Chad)
Comment updates (requested by Chad)
Modified commit message
Commit message from Chad explaining the MCS height change (Chad)

Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Neil Roberts <neil@linux.intel.com>
Reviewed-by: Chad Versace <chad.versace@intel.com>

1 files changed, 10 insertions, 3 deletions

diff --git a/src/mesa/drivers/dri/i965/intel_mipmap_tree.h b/src/mesa/drivers/dri/i965/intel_mipmap_tree.h
index 805cd71..64f73ea 100644
--- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.h
+++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.h
@@ -633,15 +633,22 @@ struct intel_mipmap_tree
     * The SURFACE_STATE bits associated with the last fast color clear to this
     * color mipmap tree, if any.
     *
-    * This value will only ever contain ones in bits 28-31, so it is safe to
-    * OR into dword 7 of SURFACE_STATE.
+    * Prior to GEN9 there is a single bit for RGBA clear values which gives you
+    * the option of 2^4 clear colors. Each bit determines if the color channel
+    * is fully saturated or unsaturated (Cherryview does add a 32b value per
+    * channel, but it is globally applied instead of being part of the render
+    * surface state). Starting with GEN9, the surface state accepts a 32b value
+    * for each color channel.
     *
     * @see RENDER_SURFACE_STATE.RedClearColor
     * @see RENDER_SURFACE_STATE.GreenClearColor
     * @see RENDER_SURFACE_STATE.BlueClearColor
     * @see RENDER_SURFACE_STATE.AlphaClearColor
     */
-   uint32_t fast_clear_color_value;
+   union {
+      uint32_t fast_clear_color_value;
+      union gl_color_union gen9_fast_clear_color;
+   };
 
    /**
     * Disable allocation of auxiliary buffers, such as the HiZ buffer and MCS