From b61c5b884d4decfe60c4a66118900c721bb79da5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@linux.intel.com>
Date: Fri, 13 Mar 2020 18:20:49 +0200
Subject: drm/edid: Return DispID length from drm_find_displayid_extension()
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Git-commit: 23b03867a2201099f598a6d7800f7837620dfa94
Patch-mainline: v5.8-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322

As with the byte offset (idx) drm_find_displayid_extension() is
the only one who actually knows how much data the resulting DispID
block can contain. So return the length from therein instead of
assuming it's the EDID block length all over.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200313162054.16009-5-ville.syrjala@linux.intel.com
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/drm_edid.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 5f87bb42557a..1717d57f6b11 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -3213,13 +3213,15 @@ static u8 *drm_find_edid_extension(const struct edid *edid, int ext_id)
 }
 
 
-static u8 *drm_find_displayid_extension(const struct edid *edid, int *idx)
+static u8 *drm_find_displayid_extension(const struct edid *edid,
+					int *length, int *idx)
 {
 	u8 *displayid = drm_find_edid_extension(edid, DISPLAYID_EXT);
 
 	if (!displayid)
 		return NULL;
 
+	*length = EDID_LENGTH;
 	*idx = 1;
 
 	return displayid;
@@ -3228,8 +3230,7 @@ static u8 *drm_find_displayid_extension(const struct edid *edid, int *idx)
 static u8 *drm_find_cea_extension(const struct edid *edid)
 {
 	int ret;
-	int idx;
-	int length = EDID_LENGTH;
+	int length, idx;
 	struct displayid_block *block;
 	u8 *cea;
 	u8 *displayid;
@@ -3240,7 +3241,7 @@ static u8 *drm_find_cea_extension(const struct edid *edid)
 		return cea;
 
 	/* CEA blocks can also be found embedded in a DisplayID block */
-	displayid = drm_find_displayid_extension(edid, &idx);
+	displayid = drm_find_displayid_extension(edid, &length, &idx);
 	if (!displayid)
 		return NULL;
 
@@ -5189,12 +5190,11 @@ static int add_displayid_detailed_modes(struct drm_connector *connector,
 {
 	u8 *displayid;
 	int ret;
-	int idx;
-	int length = EDID_LENGTH;
+	int length, idx;
 	struct displayid_block *block;
 	int num_modes = 0;
 
-	displayid = drm_find_displayid_extension(edid, &idx);
+	displayid = drm_find_displayid_extension(edid, &length, &idx);
 	if (!displayid)
 		return 0;
 
@@ -5882,17 +5882,17 @@ static void drm_get_displayid(struct drm_connector *connector,
 			      struct edid *edid)
 {
 	void *displayid = NULL;
-	int idx;
+	int length, idx;
 	int ret;
 
 	connector->has_tile = false;
-	displayid = drm_find_displayid_extension(edid, &idx);
+	displayid = drm_find_displayid_extension(edid, &length, &idx);
 	if (!displayid) {
 		/* drop reference to any tile group we had */
 		goto out_drop_ref;
 	}
 
-	ret = drm_parse_display_id(connector, displayid, EDID_LENGTH, idx);
+	ret = drm_parse_display_id(connector, displayid, length, idx);
 	if (ret < 0)
 		goto out_drop_ref;
 	if (!connector->has_tile)
-- 
2.28.0