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

drivers/gpu/drm/radeon/cik.c

@@ -3114,6 +3114,8 @@ static void cik_setup_rb(struct radeon_device *rdev,
 		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;

drivers/gpu/drm/radeon/radeon.h

@@ -1940,7 +1940,7 @@ struct si_asic {
 	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 @@ struct cik_asic {
 	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;

drivers/gpu/drm/radeon/radeon_kms.c

@@ -461,6 +461,15 @@ int radeon_info_ioctl(struct drm_device *dev, void *data, struct drm_file *filp)
 	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;

drivers/gpu/drm/radeon/si.c

@@ -2855,6 +2855,8 @@ static void si_setup_rb(struct radeon_device *rdev,
 		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;

include/uapi/drm/radeon_drm.h

@@ -983,6 +983,8 @@ struct drm_radeon_cs {
 #define RADEON_INFO_SI_CP_DMA_COMPUTE	0x17
 /* CIK macrotile mode array */
 #define RADEON_INFO_CIK_MACROTILE_MODE_ARRAY	0x18
+/* query the number of render backends */
+#define RADEON_INFO_SI_BACKEND_ENABLED_MASK	0x19
 
 
 struct drm_radeon_info {