Mesa (master): radeonsi: add a workaround for inexact SNORM8 blitting again

[Marek Olšák]

Module: Mesa
Branch: master
Commit: f9dc29a9a53e3f16cdca56e39664257082d680bc
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=f9dc29a9a53e3f16cdca56e39664257082d680bc

Author: Marek Olšák <marek.olsak at amd.com>
Date:   Sat Jun 17 00:44:05 2017 +0200

radeonsi: add a workaround for inexact SNORM8 blitting again

GFX9 is affected.

We only have tests for GL_x_SNORM where x is R8, RG8, RGB8, and RGBA8.

Reviewed-by: Nicolai Hähnle <nicolai.haehnle at amd.com>

---

 src/gallium/drivers/radeonsi/si_blit.c | 37 ++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/src/gallium/drivers/radeonsi/si_blit.c b/src/gallium/drivers/radeonsi/si_blit.c
index b240c4d355..c62efbfa7d 100644
--- a/src/gallium/drivers/radeonsi/si_blit.c
+++ b/src/gallium/drivers/radeonsi/si_blit.c
@@ -1068,6 +1068,43 @@ void si_resource_copy_region(struct pipe_context *ctx,
 		}
 	}
 
+	/* SNORM8 blitting has precision issues on some chips. Use the SINT
+	 * equivalent instead, which doesn't force DCC decompression.
+	 * Note that some chips avoid this issue by using SDMA.
+	 */
+	if (util_format_is_snorm8(dst_templ.format)) {
+		switch (dst_templ.format) {
+		case PIPE_FORMAT_R8_SNORM:
+			dst_templ.format = src_templ.format = PIPE_FORMAT_R8_SINT;
+			break;
+		case PIPE_FORMAT_R8G8_SNORM:
+			dst_templ.format = src_templ.format = PIPE_FORMAT_R8G8_SINT;
+			break;
+		case PIPE_FORMAT_R8G8B8X8_SNORM:
+			dst_templ.format = src_templ.format = PIPE_FORMAT_R8G8B8X8_SINT;
+			break;
+		case PIPE_FORMAT_R8G8B8A8_SNORM:
+		/* There are no SINT variants for ABGR and XBGR, so we have to use RGBA. */
+		case PIPE_FORMAT_A8B8G8R8_SNORM:
+		case PIPE_FORMAT_X8B8G8R8_SNORM:
+			dst_templ.format = src_templ.format = PIPE_FORMAT_R8G8B8A8_SINT;
+			break;
+		case PIPE_FORMAT_A8_SNORM:
+			dst_templ.format = src_templ.format = PIPE_FORMAT_A8_SINT;
+			break;
+		case PIPE_FORMAT_L8_SNORM:
+			dst_templ.format = src_templ.format = PIPE_FORMAT_L8_SINT;
+			break;
+		case PIPE_FORMAT_L8A8_SNORM:
+			dst_templ.format = src_templ.format = PIPE_FORMAT_L8A8_SINT;
+			break;
+		case PIPE_FORMAT_I8_SNORM:
+			dst_templ.format = src_templ.format = PIPE_FORMAT_I8_SINT;
+			break;
+		default:; /* fall through */
+		}
+	}
+
 	vi_disable_dcc_if_incompatible_format(&sctx->b, dst, dst_level,
 					      dst_templ.format);
 	vi_disable_dcc_if_incompatible_format(&sctx->b, src, src_level,