[PATCH v5 12/14] drm/edid: introduce a helper that compares edid data from two drm_edid

[Melissa Wen <mwen@igalia.com>]

AMD driver has a function used to compare if two edid are the same; this
is useful to some of the link detection algorithms implemented by
amdgpu. Since the amdgpu function can be helpful for other drivers, this
commit abstracts the AMD function to make it available at the DRM level
by wrapping existent drm_edid_eq().

v2:
- rename drm_edid_eq to drm_edid_eq_buf (jani)
- add NULL checks (jani)

v3:
- fix kernel-doc (jani)
- fix parameter names

Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Co-developed-by: Rodrigo Siqueira <siqueira@igalia.com>
Signed-off-by: Rodrigo Siqueira <siqueira@igalia.com>
Signed-off-by: Melissa Wen <mwen@igalia.com>
---
 drivers/gpu/drm/drm_edid.c | 24 +++++++++++++++++++++---
 include/drm/drm_edid.h     |  2 ++
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index d5772a3d27f1..056e070b2f55 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -1820,8 +1820,8 @@ static bool edid_block_is_zero(const void *edid)
 	return mem_is_zero(edid, EDID_LENGTH);
 }
 
-static bool drm_edid_eq(const struct drm_edid *drm_edid,
-			const void *raw_edid, size_t raw_edid_size)
+static bool drm_edid_eq_buf(const struct drm_edid *drm_edid,
+			    const void *raw_edid, size_t raw_edid_size)
 {
 	bool edid1_present = drm_edid && drm_edid->edid && drm_edid->size;
 	bool edid2_present = raw_edid && raw_edid_size;
@@ -6915,7 +6915,7 @@ static int _drm_edid_connector_property_update(struct drm_connector *connector,
 		const void *old_edid = connector->edid_blob_ptr->data;
 		size_t old_edid_size = connector->edid_blob_ptr->length;
 
-		if (old_edid && !drm_edid_eq(drm_edid, old_edid, old_edid_size)) {
+		if (old_edid && !drm_edid_eq_buf(drm_edid, old_edid, old_edid_size)) {
 			connector->epoch_counter++;
 			drm_dbg_kms(dev, "[CONNECTOR:%d:%s] EDID changed, epoch counter %llu\n",
 				    connector->base.id, connector->name,
@@ -7520,3 +7520,21 @@ bool drm_edid_is_digital(const struct drm_edid *drm_edid)
 		drm_edid->edid->input & DRM_EDID_INPUT_DIGITAL;
 }
 EXPORT_SYMBOL(drm_edid_is_digital);
+
+/**
+ * drm_edid_eq - Check if EDIDs are equal
+ *
+ * @drm_edid_1: first drm_edid to compare edid
+ * @drm_edid_2: second drm_edid to compare edid
+ *
+ * Return true if EDIDs are equal.
+ */
+bool drm_edid_eq(const struct drm_edid *drm_edid_1,
+		 const struct drm_edid *drm_edid_2)
+{
+	const void *edid_1 = drm_edid_1 ? drm_edid_1->edid : NULL;
+	size_t edid_1_size = drm_edid_1 ? drm_edid_1->size : 0;
+
+	return drm_edid_eq_buf(drm_edid_2, edid_1, edid_1_size);
+}
+EXPORT_SYMBOL(drm_edid_eq);
diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
index 960592167486..8617d2285f38 100644
--- a/include/drm/drm_edid.h
+++ b/include/drm/drm_edid.h
@@ -469,6 +469,8 @@ int drm_edid_connector_update(struct drm_connector *connector,
 			      const struct drm_edid *edid);
 int drm_edid_connector_add_modes(struct drm_connector *connector);
 bool drm_edid_is_digital(const struct drm_edid *drm_edid);
+bool drm_edid_eq(const struct drm_edid *drm_edid_1,
+		 const struct drm_edid *drm_edid_2);
 void drm_edid_get_product_id(const struct drm_edid *drm_edid,
 			     struct drm_edid_product_id *id);
 void drm_edid_print_product_id(struct drm_printer *p,
-- 
2.47.2