drm/radeon/kms: fix extended lvds info parsing

commit 05fa7ea upstream.

On rev <= 1.1 tables, the offset is absolute,
on newer tables, it's relative.

Fixes:
https://bugzilla.redhat.com/show_bug.cgi?id=700326

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/gpu/drm/radeon/radeon_atombios.c

@@ -1574,9 +1574,17 @@ struct radeon_encoder_atom_dig *radeon_atombios_get_lvds_info(struct
 			ATOM_FAKE_EDID_PATCH_RECORD *fake_edid_record;
 			ATOM_PANEL_RESOLUTION_PATCH_RECORD *panel_res_record;
 			bool bad_record = false;
-			u8 *record = (u8 *)(mode_info->atom_context->bios +
-					    data_offset +
-					    le16_to_cpu(lvds_info->info.usModePatchTableOffset));
+			u8 *record;
+
+			if ((frev == 1) && (crev < 2))
+				/* absolute */
+				record = (u8 *)(mode_info->atom_context->bios +
+						le16_to_cpu(lvds_info->info.usModePatchTableOffset));
+			else
+				/* relative */
+				record = (u8 *)(mode_info->atom_context->bios +
+						data_offset +
+						le16_to_cpu(lvds_info->info.usModePatchTableOffset));
 			while (*record != ATOM_RECORD_END_TYPE) {
 				switch (*record) {
 				case LCD_MODE_PATCH_RECORD_MODE_TYPE: