[Mesa-dev] [PATCH 22/23] i965: Add helper for checking for lossless compressible

[Topi Pohjolainen]

Signed-off-by: Topi Pohjolainen <topi.pohjolainen at intel.com>
---
 src/mesa/drivers/dri/i965/intel_mipmap_tree.c | 21 +++++++++++++++++++++
 src/mesa/drivers/dri/i965/intel_mipmap_tree.h |  3 +++
 2 files changed, 24 insertions(+)

diff --git a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
index 1fd2654..59961f2 100644
--- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
+++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
@@ -270,6 +270,27 @@ intel_miptree_supports_non_msrt_fast_clear(struct brw_context *brw,
       return true;
 }
 
+bool
+intel_miptree_supports_lossless_compressed(mesa_format format)
+{
+   /* For now compression is only enabled for integer formats even though
+    * there exist supported floating point formats also. This is a heuristic
+    * decision based on current public benchmarks. In none of the cases these
+    * formats provided any improvement but a few cases were seen to regress.
+    * Hence these are left to to be enabled in the future when they are known
+    * to improve things.
+    */
+   if (!_mesa_is_format_integer_color(format))
+      return false;
+
+   /* In principle, fast clear mechanism and lossless compression go hand in
+    * hand. However, 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.
+    */
+   return _mesa_get_srgb_format_linear(format) == format;
+}
 
 /**
  * Determine depth format corresponding to a depth+stencil format,
diff --git a/src/mesa/drivers/dri/i965/intel_mipmap_tree.h b/src/mesa/drivers/dri/i965/intel_mipmap_tree.h
index f05436d..3a1ecd2 100644
--- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.h
+++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.h
@@ -684,6 +684,9 @@ intel_miptree_supports_non_msrt_fast_clear(struct brw_context *brw,
                                            const struct intel_mipmap_tree *mt);
 
 bool
+intel_miptree_supports_lossless_compressed(mesa_format format);
+
+bool
 intel_miptree_alloc_non_msrt_mcs(struct brw_context *brw,
                                  struct intel_mipmap_tree *mt);
 
-- 
2.5.0