radeonsi: properly compute an LS-HS thread group size limit

"64 / max * 4" is less than "64 * 4 / max".

Tested-by: Dieter Nützel <Dieter@nuetzel-hh.de>

diff --git a/src/gallium/drivers/radeonsi/si_state_draw.c b/src/gallium/drivers/radeonsi/si_state_draw.c
index 942cb3c..e7f8389 100644 (file)
--- a/src/gallium/drivers/radeonsi/si_state_draw.c
+++ b/src/gallium/drivers/radeonsi/si_state_draw.c
@@ -146,7 +146,8 @@ static bool si_emit_derived_tess_state(struct si_context *sctx,
         * resource usage. Also ensures that the number of tcs in and out
         * vertices per threadgroup are at most 256.
         */
-       *num_patches = 64 / MAX2(num_tcs_input_cp, num_tcs_output_cp) * 4;
+       unsigned max_verts_per_patch = MAX2(num_tcs_input_cp, num_tcs_output_cp);
+       *num_patches = 256 / max_verts_per_patch;
 
        /* Make sure that the data fits in LDS. This assumes the shaders only
         * use LDS for the inputs and outputs.
@@ -173,7 +174,7 @@ static bool si_emit_derived_tess_state(struct si_context *sctx,
                /* SI bug workaround, related to power management. Limit LS-HS
                 * threadgroups to only one wave.
                 */
-               unsigned one_wave = 64 / MAX2(num_tcs_input_cp, num_tcs_output_cp);
+               unsigned one_wave = 64 / max_verts_per_patch;
                *num_patches = MIN2(*num_patches, one_wave);
        }