[Mesa-dev] [RFC 1/2] intel/isl: Disable some gen10 CCS_E formats for now

[Nanley Chery]

CannonLake additionally supports R11G11B10_FLOAT and four 10-10-10-2
formats with CCS_E. None of these formats fit within the current
blorp_copy framework so disable them until support is added.

Signed-off-by: Nanley Chery <nanley.g.chery at intel.com>
Cc: Jason Ekstrand <jason at jlekstrand.net>
---

Jason, do you think we modify blorp instead of moving forward with this
patch? In any case, I've sent this to the list to add context to my next
patch.

 src/intel/isl/isl_format.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/src/intel/isl/isl_format.c b/src/intel/isl/isl_format.c
index fba3ac5e1a..03c591071b 100644
--- a/src/intel/isl/isl_format.c
+++ b/src/intel/isl/isl_format.c
@@ -536,6 +536,30 @@ isl_format_supports_ccs_e(const struct gen_device_info *devinfo,
    if (!format_info[format].exists)
       return false;
 
+   /* For simplicity, only report that a format supports CCS_E if blorp can
+    * perform bit-for-bit copies with an image of that format while compressed.
+    * This allows ISL users to avoid having to resolve the image before
+    * performing such a copy. We may want to change this behavior in the
+    * future.
+    *
+    * R11G11B10_FLOAT has no equivalent UINT format. Given how blorp_copy
+    * currently works, bit-for-bit copy operations are not possible without an
+    * intermediate resolve.
+    */
+   if (format == ISL_FORMAT_R11G11B10_FLOAT)
+      return false;
+
+   /* blorp_copy currently doesn't support formats with different bit-widths
+    * per-channel. Until that support is added, report that these formats don't
+    * support CCS_E. FIXME: Add support for these formats.
+    */
+   if (format == ISL_FORMAT_B10G10R10A2_UNORM ||
+       format == ISL_FORMAT_B10G10R10A2_UNORM_SRGB ||
+       format == ISL_FORMAT_R10G10B10A2_UNORM ||
+       format == ISL_FORMAT_R10G10B10A2_UINT) {
+      return false;
+   }
+
    return format_gen(devinfo) >= format_info[format].ccs_e;
 }
 
-- 
2.14.3