1 files changed, 53 insertions, 9 deletions

diff --git a/drivers/gpu/drm/drm_displayid.c b/drivers/gpu/drm/drm_displayid.c
index 38ea8203df45..9edc111be7ee 100644
--- a/drivers/gpu/drm/drm_displayid.c
+++ b/drivers/gpu/drm/drm_displayid.c
@@ -7,13 +7,29 @@
 #include <drm/drm_edid.h>
 #include <drm/drm_print.h>
 
-static int validate_displayid(const u8 *displayid, int length, int idx)
+static const struct displayid_header *
+displayid_get_header(const u8 *displayid, int length, int index)
+{
+	const struct displayid_header *base;
+
+	if (sizeof(*base) > length - index)
+		return ERR_PTR(-EINVAL);
+
+	base = (const struct displayid_header *)&displayid[index];
+
+	return base;
+}
+
+static const struct displayid_header *
+validate_displayid(const u8 *displayid, int length, int idx)
 {
 	int i, dispid_length;
 	u8 csum = 0;
 	const struct displayid_header *base;
 
-	base = (const struct displayid_header *)&displayid[idx];
+	base = displayid_get_header(displayid, length, idx);
+	if (IS_ERR(base))
+		return base;
 
 	DRM_DEBUG_KMS("base revision 0x%x, length %d, %d %d\n",
 		      base->rev, base->bytes, base->prod_id, base->ext_count);
@@ -21,16 +37,16 @@ static int validate_displayid(const u8 *displayid, int length, int idx)
 	/* +1 for DispID checksum */
 	dispid_length = sizeof(*base) + base->bytes + 1;
 	if (dispid_length > length - idx)
-		return -EINVAL;
+		return ERR_PTR(-EINVAL);
 
 	for (i = 0; i < dispid_length; i++)
 		csum += displayid[idx + i];
 	if (csum) {
 		DRM_NOTE("DisplayID checksum invalid, remainder is %d\n", csum);
-		return -EINVAL;
+		return ERR_PTR(-EINVAL);
 	}
 
-	return 0;
+	return base;
 }
 
 static const u8 *drm_find_displayid_extension(const struct drm_edid *drm_edid,
@@ -39,7 +55,6 @@ static const u8 *drm_find_displayid_extension(const struct drm_edid *drm_edid,
 {
 	const u8 *displayid = drm_find_edid_extension(drm_edid, DISPLAYID_EXT, ext_index);
 	const struct displayid_header *base;
-	int ret;
 
 	if (!displayid)
 		return NULL;
@@ -48,11 +63,10 @@ static const u8 *drm_find_displayid_extension(const struct drm_edid *drm_edid,
 	*length = EDID_LENGTH - 1;
 	*idx = 1;
 
-	ret = validate_displayid(displayid, *length, *idx);
-	if (ret)
+	base = validate_displayid(displayid, *length, *idx);
+	if (IS_ERR(base))
 		return NULL;
 
-	base = (const struct displayid_header *)&displayid[*idx];
 	*length = *idx + sizeof(*base) + base->bytes;
 
 	return displayid;
@@ -109,6 +123,9 @@ __displayid_iter_next(struct displayid_iter *iter)
 	}
 
 	for (;;) {
+		/* The first section we encounter is the base section */
+		bool base_section = !iter->section;
+
 		iter->section = drm_find_displayid_extension(iter->drm_edid,
 							     &iter->length,
 							     &iter->idx,
@@ -118,6 +135,18 @@ __displayid_iter_next(struct displayid_iter *iter)
 			return NULL;
 		}
 
+		/* Save the structure version and primary use case. */
+		if (base_section) {
+			const struct displayid_header *base;
+
+			base = displayid_get_header(iter->section, iter->length,
+						    iter->idx);
+			if (!IS_ERR(base)) {
+				iter->version = base->rev;
+				iter->primary_use = base->prod_id;
+			}
+		}
+
 		iter->idx += sizeof(struct displayid_header);
 
 		block = displayid_iter_block(iter);
@@ -130,3 +159,18 @@ void displayid_iter_end(struct displayid_iter *iter)
 {
 	memset(iter, 0, sizeof(*iter));
 }
+
+/* DisplayID Structure Version/Revision from the Base Section. */
+u8 displayid_version(const struct displayid_iter *iter)
+{
+	return iter->version;
+}
+
+/*
+ * DisplayID Primary Use Case (2.0+) or Product Type Identifier (1.0-1.3) from
+ * the Base Section.
+ */
+u8 displayid_primary_use(const struct displayid_iter *iter)
+{
+	return iter->primary_use;
+}