drm_edid_to_eld: check for CEA data blocks only from structure revision 3 on

CEA datablocks are only defined from revision 3 onwards. Only check for
them if the revision says so.

Signed-of-by: Christian Schmidt <schmidt@digadd.de>
Tested-by: James Cloos <cloos@jhcloos.com>

Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 22 insertions, 19 deletions

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 2283631c9a51..478b122ad1ba 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -1474,26 +1474,29 @@ void drm_edid_to_eld(struct drm_connector *connector, struct edid *edid)
         eld[18] = edid->prod_code[0];
         eld[19] = edid->prod_code[1];
 
-        for (db = cea + 4; db < cea + cea[2]; db += dbl + 1) {
-                dbl = db[0] & 0x1f;
-
-                switch ((db[0] & 0xe0) >> 5) {
-                case AUDIO_BLOCK:       /* Audio Data Block, contains SADs */
-                        sad_count = dbl / 3;
-                        memcpy(eld + 20 + mnl, &db[1], dbl);
-                        break;
-                case SPEAKER_BLOCK:     /* Speaker Allocation Data Block */
-                        eld[7] = db[1];
-                        break;
-                case VENDOR_BLOCK:
-                        /* HDMI Vendor-Specific Data Block */
-                        if (db[1] == 0x03 && db[2] == 0x0c && db[3] == 0)
-                                parse_hdmi_vsdb(connector, db);
-                        break;
-                default:
-                        break;
+        if (cea[1] >= 3)
+                for (db = cea + 4; db < cea + cea[2]; db += dbl + 1) {
+                        dbl = db[0] & 0x1f;
+                        
+                        switch ((db[0] & 0xe0) >> 5) {
+                        case AUDIO_BLOCK:
+                                /* Audio Data Block, contains SADs */
+                                sad_count = dbl / 3;
+                                memcpy(eld + 20 + mnl, &db[1], dbl);
+                                break;
+                        case SPEAKER_BLOCK:
+                                /* Speaker Allocation Data Block */
+                                eld[7] = db[1];
+                                break;
+                        case VENDOR_BLOCK:
+                                /* HDMI Vendor-Specific Data Block */
+                                if (db[1] == 0x03 && db[2] == 0x0c && db[3] == 0)
+                                        parse_hdmi_vsdb(connector, db);
+                                break;
+                        default:
+                                break;
+                        }
                 }
-        }
         eld[5] |= sad_count << 4;
         eld[2] = (20 + mnl + sad_count * 3 + 3) / 4;