[PATCH 2/4] drm/displayid: Iterate over all DisplayID blocks

[Dave Airlie <airlied@gmail.com>]

From: Tomas Bzatek <tomas@bzatek.net>

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>
Signed-off-by: Dave Airlie <airlied@redhat.com>
---
 drivers/gpu/drm/drm_edid.c | 30 ++++++++++++++++++------------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 9dbaaf4..3cf17a3 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -4237,18 +4237,24 @@ 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;
-	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;
+		default:
+			DRM_DEBUG_KMS("found DisplayID tag 0x%x, unhandled\n", block->tag);
+			break;
+		}
 	}
 	return 0;
 }
-- 
2.5.5

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