From 0cf5bc85b75523bf43d52ae5741dacf8ce45b4fc Mon Sep 17 00:00:00 2001
From: Jani Nikula <jani.nikula@intel.com>
Date: Wed, 8 Jun 2022 10:50:33 +0300
Subject: drm/edid: add block count and data helper functions for drm_edid
Git-commit: d9307f27efa531f034862bccf2985c5fa22c4b80
Patch-mainline: v6.0-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225 jsc#PED-2849

Add drm_edid based block count and data access helper functions that
take the EDID allocated size into account.

At the moment, the allocated size should always match the EDID size
indicated by the extension count, but this will change in the future.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1a68c8667a88e7c451b001ad8bd86c8badb57fb8.1654674560.git.jani.nikula@intel.com
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/drm_edid.c | 42 +++++++++++++++++++++++++++++++-------
 1 file changed, 35 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 002816509fc8..f44ada4bfa5b 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -1613,6 +1613,35 @@ static const void *edid_extension_block_data(const struct edid *edid, int index)
 	return edid_block_data(edid, index + 1);
 }
 
+static int drm_edid_block_count(const struct drm_edid *drm_edid)
+{
+	int num_blocks;
+
+	/* Starting point */
+	num_blocks = edid_block_count(drm_edid->edid);
+
+	/* Limit by allocated size */
+	num_blocks = min(num_blocks, (int)drm_edid->size / EDID_LENGTH);
+
+	return num_blocks;
+}
+
+static int drm_edid_extension_block_count(const struct drm_edid *drm_edid)
+{
+	return drm_edid_block_count(drm_edid) - 1;
+}
+
+static const void *drm_edid_block_data(const struct drm_edid *drm_edid, int index)
+{
+	return edid_block_data(drm_edid->edid, index);
+}
+
+static const void *drm_edid_extension_block_data(const struct drm_edid *drm_edid,
+						 int index)
+{
+	return edid_extension_block_data(drm_edid->edid, index);
+}
+
 /*
  * Initializer helper for legacy interfaces, where we have no choice but to
  * trust edid size. Not for general purpose use.
@@ -1665,8 +1694,8 @@ static const void *__drm_edid_iter_next(struct drm_edid_iter *iter)
 	if (!iter->drm_edid)
 		return NULL;
 
-	if (iter->index < edid_block_count(iter->drm_edid->edid))
-		block = edid_block_data(iter->drm_edid->edid, iter->index++);
+	if (iter->index < drm_edid_block_count(iter->drm_edid))
+		block = drm_edid_block_data(iter->drm_edid, iter->index++);
 
 	return block;
 }
@@ -3574,22 +3603,21 @@ static int add_detailed_modes(struct drm_connector *connector,
 const u8 *drm_find_edid_extension(const struct drm_edid *drm_edid,
 				  int ext_id, int *ext_index)
 {
-	const struct edid *edid = drm_edid ? drm_edid->edid : NULL;
 	const u8 *edid_ext = NULL;
 	int i;
 
 	/* No EDID or EDID extensions */
-	if (!edid || !edid_extension_block_count(edid))
+	if (!drm_edid || !drm_edid_extension_block_count(drm_edid))
 		return NULL;
 
 	/* Find CEA extension */
-	for (i = *ext_index; i < edid_extension_block_count(edid); i++) {
-		edid_ext = edid_extension_block_data(edid, i);
+	for (i = *ext_index; i < drm_edid_extension_block_count(drm_edid); i++) {
+		edid_ext = drm_edid_extension_block_data(drm_edid, i);
 		if (edid_block_tag(edid_ext) == ext_id)
 			break;
 	}
 
-	if (i >= edid_extension_block_count(edid))
+	if (i >= drm_edid_extension_block_count(drm_edid))
 		return NULL;
 
 	*ext_index = i + 1;
-- 
2.38.1