Commit 55dc449a authored by Thomas Zimmermann's avatar Thomas Zimmermann
Browse files

drm/ast: Handle failed I2C initialization gracefully 



I2C initialization is allowed to fail. In this case, create a connector
without DDC adapter. The current code would dereference a NULL pointer.

Reading the modes from the connector is supposed to work without I2C
adapter. Add the respective test.

v2:
	* init edid to NULL to avoid uninitialized read (Dan)

Signed-off-by: default avatarThomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: default avatarMaxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20211206091125.29501-2-tzimmermann@suse.de
parent d619f38c

drivers/gpu/drm/ast/ast_mode.c

+10 −7
Original line number Diff line number Diff line
@@ -1210,9 +1210,9 @@ static int ast_get_modes(struct drm_connector *connector) 
{

	struct ast_connector *ast_connector = to_ast_connector(connector);

	struct ast_private *ast = to_ast_private(connector->dev);

	struct edid *edid;

	int ret;

	struct edid *edid = NULL;

	bool flags = false;

	int ret;



	if (ast->tx_chip_type == AST_TX_DP501) {

		ast->dp501_maxclk = 0xff;
@@ -1226,7 +1226,7 @@ static int ast_get_modes(struct drm_connector *connector) 
		else

			kfree(edid);

	}

	if (!flags)

	if (!flags && ast_connector->i2c)

		edid = drm_get_edid(connector, &ast_connector->i2c->adapter);

	if (edid) {

		drm_connector_update_edid_property(&ast_connector->base, edid);
@@ -1332,10 +1332,13 @@ static int ast_connector_init(struct drm_device *dev) 
	if (!ast_connector->i2c)

		drm_err(dev, "failed to add ddc bus for connector\n");



	drm_connector_init_with_ddc(dev, connector,

				    &ast_connector_funcs,

	if (ast_connector->i2c)

		drm_connector_init_with_ddc(dev, connector, &ast_connector_funcs,

					    DRM_MODE_CONNECTOR_VGA,

					    &ast_connector->i2c->adapter);

	else

		drm_connector_init(dev, connector, &ast_connector_funcs,

				   DRM_MODE_CONNECTOR_VGA);



	drm_connector_helper_add(connector, &ast_connector_helper_funcs);