drm/displayid: Iterate over all DisplayID blocks

This will iterate over all DisplayID blocks found in the buffer.
Previously only the first block was parsed.

https://bugs.freedesktop.org/show_bug.cgi?id=95207

Signed-off-by: Tomas Bzatek <tomas@bzatek.net>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 19 insertions, 13 deletions

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 4724596ebf53..0b95a7f2db03 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -4237,19 +4237,25 @@ static int drm_parse_display_id(struct drm_connector *connector,
                 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:
-                ret = drm_parse_tiled_block(connector, block);
-                if (ret)
-                        return ret;
-                break;
-        default:
-                printk("unknown displayid tag %d\n", block->tag);
-                break;
+        idx += sizeof(struct displayid_hdr);
+        while (block = (struct displayid_block *)&displayid[idx],
+               idx + sizeof(struct displayid_block) <= length &&
+               idx + sizeof(struct displayid_block) + block->num_bytes <= length &&
+               block->num_bytes > 0) {
+                idx += block->num_bytes + sizeof(struct displayid_block);
+                DRM_DEBUG_KMS("block id 0x%x, rev %d, len %d\n",
+                              block->tag, block->rev, block->num_bytes);
+
+                switch (block->tag) {
+                case DATA_BLOCK_TILED_DISPLAY:
+                        ret = drm_parse_tiled_block(connector, block);
+                        if (ret)
+                                return ret;
+                        break;
+                default:
+                        DRM_DEBUG_KMS("found DisplayID tag 0x%x, unhandled\n", block->tag);
+                        break;
+                }
         }
         return 0;
 }