drm/msm/a5xx: Disable flat shading optimization

Port over the command from downstream to prevent undefined
behaviour.
Signed-off-by: Konrad Dybcio <konrad.dybcio@somainline.org>
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
Reviewed-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/adreno/a5xx_gpu.c

@@ -791,6 +791,9 @@ static int a5xx_hw_init(struct msm_gpu *gpu)
 	    adreno_is_a540(adreno_gpu))
 		gpu_write(gpu, REG_A5XX_UCHE_DBG_ECO_CNTL_2, regbit);
 
+	/* Disable All flat shading optimization (ALLFLATOPTDIS) */
+	gpu_rmw(gpu, REG_A5XX_VPC_DBG_ECO_CNTL, 0, (1 << 10));
+
 	/* Protect registers from the CP */
 	gpu_write(gpu, REG_A5XX_CP_PROTECT_CNTL, 0x00000007);