drm: Add helper to compare edids.
Many drivers would benefit from using
drm helper to compare edid, rather
than bothering with own implementation.
v2: Added documentation for this function.
Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200630002700.5451-2-kunal1.joshi@intel.com
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 71ae0cd..920ac9e 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -1616,6 +1616,39 @@ static bool drm_edid_is_zero(const u8 *in_edid, int length)
}
/**
+ * drm_edid_are_equal - compare two edid blobs.
+ * @edid1: pointer to first blob
+ * @edid2: pointer to second blob
+ * This helper can be used during probing to determine if
+ * edid had changed.
+ */
+bool drm_edid_are_equal(const struct edid *edid1, const struct edid *edid2)
+{
+ int edid1_len, edid2_len;
+ bool edid1_present = edid1 != NULL;
+ bool edid2_present = edid2 != NULL;
+
+ if (edid1_present != edid2_present)
+ return false;
+
+ if (edid1) {
+
+ edid1_len = EDID_LENGTH * (1 + edid1->extensions);
+ edid2_len = EDID_LENGTH * (1 + edid2->extensions);
+
+ if (edid1_len != edid2_len)
+ return false;
+
+ if (memcmp(edid1, edid2, edid1_len))
+ return false;
+ }
+
+ return true;
+}
+EXPORT_SYMBOL(drm_edid_are_equal);
+
+
+/**
* drm_edid_block_valid - Sanity check the EDID block (base or extension)
* @raw_edid: pointer to raw EDID block
* @block: type of block to validate (0 for base, extension otherwise)