drm/radeon: Fix num_banks calculation for SI

The way the tile mode array index was calculated only makes sense for
the CIK specific macrotile mode array. For SI, we need to use one of the
tile mode array indices reserved for displayable surfaces.

This happened to result in correct display most if not all of the time
because most of the SI tiling modes use the same number of banks.
Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>

drivers/gpu/drm/radeon/atombios_crtc.c

@@ -1177,16 +1177,18 @@ static int dce4_crtc_do_set_base(struct drm_crtc *crtc,
 
 		/* Set NUM_BANKS. */
 		if (rdev->family >= CHIP_TAHITI) {
-			unsigned tileb, index, num_banks, tile_split_bytes;
+			unsigned index, num_banks;
+
+			if (rdev->family >= CHIP_BONAIRE) {
+				unsigned tileb, tile_split_bytes;
 
 				/* Calculate the macrotile mode index. */
 				tile_split_bytes = 64 << tile_split;
 				tileb = 8 * 8 * target_fb->bits_per_pixel / 8;
 				tileb = min(tile_split_bytes, tileb);
 
-			for (index = 0; tileb > 64; index++) {
+				for (index = 0; tileb > 64; index++)
 					tileb >>= 1;
-			}
 
 				if (index >= 16) {
 					DRM_ERROR("Wrong screen bpp (%u) or tile split (%u)\n",
@@ -1194,10 +1196,24 @@ static int dce4_crtc_do_set_base(struct drm_crtc *crtc,
 					return -EINVAL;
 				}
 
-			if (rdev->family >= CHIP_BONAIRE)
 				num_banks = (rdev->config.cik.macrotile_mode_array[index] >> 6) & 0x3;
-			else
+			} else {
+				switch (target_fb->bits_per_pixel) {
+				case 8:
+					index = 10;
+					break;
+				case 16:
+					index = SI_TILE_MODE_COLOR_2D_SCANOUT_16BPP;
+					break;
+				default:
+				case 32:
+					index = SI_TILE_MODE_COLOR_2D_SCANOUT_32BPP;
+					break;
+				}
+
 				num_banks = (rdev->config.si.tile_mode_array[index] >> 20) & 0x3;
+			}
+
 			fb_format |= EVERGREEN_GRPH_NUM_BANKS(num_banks);
 		} else {
 			/* NI and older. */