drm/radeon: expose render backend mask to the userspace

This will allow userspace to correctly program the PA_SC_RASTER_CONFIG
register, so it can be considered a fix.

Signed-off-by: Marek Olšák <marek.olsak@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
diff --git a/drivers/gpu/drm/radeon/cik.c b/drivers/gpu/drm/radeon/cik.c
index 138a776..e950fab 100644
--- a/drivers/gpu/drm/radeon/cik.c
+++ b/drivers/gpu/drm/radeon/cik.c
@@ -3114,6 +3114,8 @@
 		mask <<= 1;
 	}
 
+	rdev->config.cik.backend_enable_mask = enabled_rbs;
+
 	for (i = 0; i < se_num; i++) {
 		cik_select_se_sh(rdev, i, 0xffffffff);
 		data = 0;
diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
index b1f990d..45e1f44 100644
--- a/drivers/gpu/drm/radeon/radeon.h
+++ b/drivers/gpu/drm/radeon/radeon.h
@@ -1940,7 +1940,7 @@
 	unsigned sc_earlyz_tile_fifo_size;
 
 	unsigned num_tile_pipes;
-	unsigned num_backends_per_se;
+	unsigned backend_enable_mask;
 	unsigned backend_disable_mask_per_asic;
 	unsigned backend_map;
 	unsigned num_texture_channel_caches;
@@ -1970,7 +1970,7 @@
 	unsigned sc_earlyz_tile_fifo_size;
 
 	unsigned num_tile_pipes;
-	unsigned num_backends_per_se;
+	unsigned backend_enable_mask;
 	unsigned backend_disable_mask_per_asic;
 	unsigned backend_map;
 	unsigned num_texture_channel_caches;
diff --git a/drivers/gpu/drm/radeon/radeon_kms.c b/drivers/gpu/drm/radeon/radeon_kms.c
index 55d0b47..21d593c 100644
--- a/drivers/gpu/drm/radeon/radeon_kms.c
+++ b/drivers/gpu/drm/radeon/radeon_kms.c
@@ -461,6 +461,15 @@
 	case RADEON_INFO_SI_CP_DMA_COMPUTE:
 		*value = 1;
 		break;
+	case RADEON_INFO_SI_BACKEND_ENABLED_MASK:
+		if (rdev->family >= CHIP_BONAIRE) {
+			*value = rdev->config.cik.backend_enable_mask;
+		} else if (rdev->family >= CHIP_TAHITI) {
+			*value = rdev->config.si.backend_enable_mask;
+		} else {
+			DRM_DEBUG_KMS("BACKEND_ENABLED_MASK is si+ only!\n");
+		}
+		break;
 	default:
 		DRM_DEBUG_KMS("Invalid request %d\n", info->request);
 		return -EINVAL;
diff --git a/drivers/gpu/drm/radeon/si.c b/drivers/gpu/drm/radeon/si.c
index 3eed9a1..85e1edf 100644
--- a/drivers/gpu/drm/radeon/si.c
+++ b/drivers/gpu/drm/radeon/si.c
@@ -2855,6 +2855,8 @@
 		mask <<= 1;
 	}
 
+	rdev->config.si.backend_enable_mask = enabled_rbs;
+
 	for (i = 0; i < se_num; i++) {
 		si_select_se_sh(rdev, i, 0xffffffff);
 		data = 0;