video: Check EDID for HDMI connection

Check EDID Vendor Specific Data Block bytes to see if the connection
is HDMI and set FB_MISC_HDMI.

Signed-off-by: David Ung <[e-mail]>
Signed-off-by: Christopher Freeman <[e-mail]>
Signed-off-by: Tomi Valkeinen <[e-mail]>

drivers/video/fbdev/core/fbmon.c

···
 	while (pos < edid[2]) {
 		u8 len = edid[pos] & 0x1f, type = (edid[pos] >> 5) & 7;
 		pr_debug("Data block %u of %u bytes\n", type, len);
-		if (type == 2)
+		if (type == 2) {
 			for (i = pos; i < pos + len; i++) {
 				u8 idx = edid[pos + i] & 0x7f;
 				svd[svd_n++] = idx;
 				pr_debug("N%sative mode #%d\n",
 					 edid[pos + i] & 0x80 ? "" : "on-n", idx);
 			}
+		} else if (type == 3 && len >= 3) {
+			/* Check Vendor Specific Data Block.  For HDMI,
+			   it is always 00-0C-03 for HDMI Licensing, LLC. */
+			if (edid[pos + 1] == 3 && edid[pos + 2] == 0xc &&
+			    edid[pos + 3] == 0)
+				specs->misc |= FB_MISC_HDMI;
+		}
 		pos += len + 1;
 	}
 

include/linux/fb.h

···
 
 #define FB_MISC_PRIM_COLOR	1
 #define FB_MISC_1ST_DETAIL	2	/* First Detailed Timing is preferred */
+#define FB_MISC_HDMI		4
 struct fb_chroma {
 	__u32 redx;	/* in fraction of 1024 */
 	__u32 greenx;