1 files changed, 97 insertions, 25 deletions

diff --git a/drivers/gpu/drm/drm_displayid.c b/drivers/gpu/drm/drm_displayid.c
index 38ea8203df45..58d0bb6d2676 100644
--- a/drivers/gpu/drm/drm_displayid.c
+++ b/drivers/gpu/drm/drm_displayid.c
@@ -3,57 +3,101 @@
  * Copyright © 2021 Intel Corporation
  */
 
-#include <drm/drm_displayid.h>
 #include <drm/drm_edid.h>
 #include <drm/drm_print.h>
 
-static int validate_displayid(const u8 *displayid, int length, int idx)
+#include "drm_crtc_internal.h"
+#include "drm_displayid_internal.h"
+
+enum {
+	QUIRK_IGNORE_CHECKSUM,
+};
+
+struct displayid_quirk {
+	const struct drm_edid_ident ident;
+	u8 quirks;
+};
+
+static const struct displayid_quirk quirks[] = {
+	{
+		.ident = DRM_EDID_IDENT_INIT('C', 'S', 'O', 5142, "MNE007ZA1-5"),
+		.quirks = BIT(QUIRK_IGNORE_CHECKSUM),
+	},
+};
+
+static u8 get_quirks(const struct drm_edid *drm_edid)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(quirks); i++) {
+		if (drm_edid_match(drm_edid, &quirks[i].ident))
+			return quirks[i].quirks;
+	}
+
+	return 0;
+}
+
+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, bool ignore_checksum)
 {
 	int i, dispid_length;
 	u8 csum = 0;
 	const struct displayid_header *base;
 
-	base = (const struct displayid_header *)&displayid[idx];
-
-	DRM_DEBUG_KMS("base revision 0x%x, length %d, %d %d\n",
-		      base->rev, base->bytes, base->prod_id, base->ext_count);
+	base = displayid_get_header(displayid, length, idx);
+	if (IS_ERR(base))
+		return base;
 
 	/* +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;
+		DRM_NOTE("DisplayID checksum invalid, remainder is %d%s\n", csum,
+			 ignore_checksum ? " (ignoring)" : "");
+
+		if (!ignore_checksum)
+			return ERR_PTR(-EINVAL);
 	}
 
-	return 0;
+	return base;
 }
 
-static const u8 *drm_find_displayid_extension(const struct drm_edid *drm_edid,
-					      int *length, int *idx,
-					      int *ext_index)
+static const u8 *find_next_displayid_extension(struct displayid_iter *iter)
 {
-	const u8 *displayid = drm_find_edid_extension(drm_edid, DISPLAYID_EXT, ext_index);
 	const struct displayid_header *base;
-	int ret;
+	const u8 *displayid;
+	bool ignore_checksum = iter->quirks & BIT(QUIRK_IGNORE_CHECKSUM);
 
+	displayid = drm_edid_find_extension(iter->drm_edid, DISPLAYID_EXT, &iter->ext_index);
 	if (!displayid)
 		return NULL;
 
 	/* EDID extensions block checksum isn't for us */
-	*length = EDID_LENGTH - 1;
-	*idx = 1;
+	iter->length = EDID_LENGTH - 1;
+	iter->idx = 1;
 
-	ret = validate_displayid(displayid, *length, *idx);
-	if (ret)
+	base = validate_displayid(displayid, iter->length, iter->idx, ignore_checksum);
+	if (IS_ERR(base))
 		return NULL;
 
-	base = (const struct displayid_header *)&displayid[*idx];
-	*length = *idx + sizeof(*base) + base->bytes;
+	iter->length = iter->idx + sizeof(*base) + base->bytes;
 
 	return displayid;
 }
@@ -64,6 +108,7 @@ void displayid_iter_edid_begin(const struct drm_edid *drm_edid,
 	memset(iter, 0, sizeof(*iter));
 
 	iter->drm_edid = drm_edid;
+	iter->quirks = get_quirks(drm_edid);
 }
 
 static const struct displayid_block *
@@ -109,15 +154,27 @@ __displayid_iter_next(struct displayid_iter *iter)
 	}
 
 	for (;;) {
-		iter->section = drm_find_displayid_extension(iter->drm_edid,
-							     &iter->length,
-							     &iter->idx,
-							     &iter->ext_index);
+		/* The first section we encounter is the base section */
+		bool base_section = !iter->section;
+
+		iter->section = find_next_displayid_extension(iter);
 		if (!iter->section) {
 			iter->drm_edid = NULL;
 			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 +187,18 @@ 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;
+}