+
+static int drm_parse_display_id(struct drm_connector *connector,
+ u8 *displayid, int length,
+ bool is_edid_extension)
+{
+ /* if this is an EDID extension the first byte will be 0x70 */
+ int idx = 0;
+ struct displayid_hdr *base;
+ struct displayid_block *block;
+ u8 csum = 0;
+ int i;
+
+ if (is_edid_extension)
+ idx = 1;
+
+ base = (struct displayid_hdr *)&displayid[idx];
+
+ DRM_DEBUG_KMS("base revision 0x%x, length %d, %d %d\n",
+ base->rev, base->bytes, base->prod_id, base->ext_count);
+
+ if (base->bytes + 5 > length - idx)
+ return -EINVAL;
+
+ for (i = idx; i <= base->bytes + 5; i++) {
+ csum += displayid[i];
+ }
+ if (csum) {
+ DRM_ERROR("DisplayID checksum invalid, remainder is %d\n", csum);
+ return -EINVAL;
+ }
+
+ block = (struct displayid_block *)&displayid[idx + 4];
+ DRM_DEBUG_KMS("block id %d, rev %d, len %d\n",
+ block->tag, block->rev, block->num_bytes);
+
+ switch (block->tag) {
+ case DATA_BLOCK_TILED_DISPLAY: {
+ struct displayid_tiled_block *tile = (struct displayid_tiled_block *)block;
+
+ u16 w, h;
+ u8 tile_v_loc, tile_h_loc;
+ u8 num_v_tile, num_h_tile;
+ struct drm_tile_group *tg;
+
+ w = tile->tile_size[0] | tile->tile_size[1] << 8;
+ h = tile->tile_size[2] | tile->tile_size[3] << 8;
+
+ num_v_tile = (tile->topo[0] & 0xf) | (tile->topo[2] & 0x30);
+ num_h_tile = (tile->topo[0] >> 4) | ((tile->topo[2] >> 2) & 0x30);
+ tile_v_loc = (tile->topo[1] & 0xf) | ((tile->topo[2] & 0x3) << 4);
+ tile_h_loc = (tile->topo[1] >> 4) | (((tile->topo[2] >> 2) & 0x3) << 4);
+
+ connector->has_tile = true;
+ if (tile->tile_cap & 0x80)
+ connector->tile_is_single_monitor = true;
+
+ connector->num_h_tile = num_h_tile + 1;
+ connector->num_v_tile = num_v_tile + 1;
+ connector->tile_h_loc = tile_h_loc;
+ connector->tile_v_loc = tile_v_loc;
+ connector->tile_h_size = w + 1;
+ connector->tile_v_size = h + 1;
+
+ DRM_DEBUG_KMS("tile cap 0x%x\n", tile->tile_cap);
+ DRM_DEBUG_KMS("tile_size %d x %d\n", w + 1, h + 1);
+ DRM_DEBUG_KMS("topo num tiles %dx%d, location %dx%d\n",
+ num_h_tile + 1, num_v_tile + 1, tile_h_loc, tile_v_loc);
+ DRM_DEBUG_KMS("vend %c%c%c\n", tile->topology_id[0], tile->topology_id[1], tile->topology_id[2]);
+
+ tg = drm_mode_get_tile_group(connector->dev, tile->topology_id);
+ if (!tg) {
+ tg = drm_mode_create_tile_group(connector->dev, tile->topology_id);
+ }
+ if (!tg)
+ return -ENOMEM;
+
+ if (connector->tile_group != tg) {
+ /* if we haven't got a pointer,
+ take the reference, drop ref to old tile group */
+ if (connector->tile_group) {
+ drm_mode_put_tile_group(connector->dev, connector->tile_group);
+ }
+ connector->tile_group = tg;
+ } else
+ /* if same tile group, then release the ref we just took. */
+ drm_mode_put_tile_group(connector->dev, tg);
+ }
+ break;
+ default:
+ printk("unknown displayid tag %d\n", block->tag);
+ break;
+ }
+ return 0;
+}
+
+static void drm_get_displayid(struct drm_connector *connector,
+ struct edid *edid)
+{
+ void *displayid = NULL;
+ int ret;
+ connector->has_tile = false;
+ displayid = drm_find_displayid_extension(edid);
+ if (!displayid) {
+ /* drop reference to any tile group we had */
+ goto out_drop_ref;
+ }
+
+ ret = drm_parse_display_id(connector, displayid, EDID_LENGTH, true);
+ if (ret < 0)
+ goto out_drop_ref;
+ if (!connector->has_tile)
+ goto out_drop_ref;
+ return;
+out_drop_ref:
+ if (connector->tile_group) {
+ drm_mode_put_tile_group(connector->dev, connector->tile_group);
+ connector->tile_group = NULL;
+ }
+ return;
+}