drm/edid: Break out reading block 0 of the EDID

A future change wants to be able to read just block 0 of the EDID, so
break it out of drm_do_get_edid() into a sub-function.

This is intended to be a no-op change--just code movement.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210914132020.v5.2.I62e76a034ac78c994d40a23cd4ec5aeee56fa77c@changeid

drivers/gpu/drm/drm_edid.c

@@ -1905,6 +1905,44 @@ int drm_add_override_edid_modes(struct drm_connector *connector)
 }
 EXPORT_SYMBOL(drm_add_override_edid_modes);
 
+static struct edid *drm_do_get_edid_base_block(
+	int (*get_edid_block)(void *data, u8 *buf, unsigned int block,
+			      size_t len),
+	void *data, bool *edid_corrupt, int *null_edid_counter)
+{
+	int i;
+	void *edid;
+
+	edid = kmalloc(EDID_LENGTH, GFP_KERNEL);
+	if (edid == NULL)
+		return NULL;
+
+	/* base block fetch */
+	for (i = 0; i < 4; i++) {
+		if (get_edid_block(data, edid, 0, EDID_LENGTH))
+			goto out;
+		if (drm_edid_block_valid(edid, 0, false, edid_corrupt))
+			break;
+		if (i == 0 && drm_edid_is_zero(edid, EDID_LENGTH)) {
+			if (null_edid_counter)
+				(*null_edid_counter)++;
+			goto carp;
+		}
+	}
+	if (i == 4)
+		goto carp;
+
+	return edid;
+
+carp:
+	kfree(edid);
+	return ERR_PTR(-EINVAL);
+
+out:
+	kfree(edid);
+	return NULL;
+}
+
 /**
  * drm_do_get_edid - get EDID data using a custom EDID block read function
  * @connector: connector we're probing
@@ -1938,25 +1976,16 @@ struct edid *drm_do_get_edid(struct drm_connector *connector,
 	if (override)
 		return override;
 
-	if ((edid = kmalloc(EDID_LENGTH, GFP_KERNEL)) == NULL)
+	edid = (u8 *)drm_do_get_edid_base_block(get_edid_block, data,
+						&connector->edid_corrupt,
+						&connector->null_edid_counter);
+	if (IS_ERR_OR_NULL(edid)) {
+		if (IS_ERR(edid))
+			connector_bad_edid(connector, edid, 1);
 		return NULL;
-
-	/* base block fetch */
-	for (i = 0; i < 4; i++) {
-		if (get_edid_block(data, edid, 0, EDID_LENGTH))
-			goto out;
-		if (drm_edid_block_valid(edid, 0, false,
-					 &connector->edid_corrupt))
-			break;
-		if (i == 0 && drm_edid_is_zero(edid, EDID_LENGTH)) {
-			connector->null_edid_counter++;
-			goto carp;
-		}
 	}
-	if (i == 4)
-		goto carp;
 
-	/* if there's no extensions, we're done */
+	/* if there's no extensions or no connector, we're done */
 	valid_extensions = edid[0x7e];
 	if (valid_extensions == 0)
 		return (struct edid *)edid;
@@ -2010,8 +2039,6 @@ struct edid *drm_do_get_edid(struct drm_connector *connector,
 
 	return (struct edid *)edid;
 
-carp:
-	connector_bad_edid(connector, edid, 1);
 out:
 	kfree(edid);
 	return NULL;