Commit 7af03e68 authored by Jani Nikula's avatar Jani Nikula
Browse files

drm/probe-helper: warn about negative .get_modes() 



The .get_modes() callback is supposed to return the number of modes,
never a negative error code. If a negative value is returned, it'll just
be interpreted as a negative count, and added to previous calculations.

Document the rules, but handle the negative values gracefully with an
error message.

Cc: stable@vger.kernel.org
Acked-by: default avatarThomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/50208c866facc33226a3c77b82bb96aeef8ef310.1709913674.git.jani.nikula@intel.com


Signed-off-by: default avatarJani Nikula <jani.nikula@intel.com>
parent dea185b7

drivers/gpu/drm/drm_probe_helper.c

+7 −0
Original line number Diff line number Diff line
@@ -422,6 +422,13 @@ static int drm_helper_probe_get_modes(struct drm_connector *connector) 


	count = connector_funcs->get_modes(connector);



	/* The .get_modes() callback should not return negative values. */

	if (count < 0) {

		drm_err(connector->dev, ".get_modes() returned %pe\n",

			ERR_PTR(count));

		count = 0;

	}



	/*

	 * Fallback for when DDC probe failed in drm_get_edid() and thus skipped

	 * override/firmware EDID.

include/drm/drm_modeset_helper_vtables.h

+2 −1
Original line number Diff line number Diff line
@@ -898,7 +898,8 @@ struct drm_connector_helper_funcs { 
	 *

	 * RETURNS:

	 *

	 * The number of modes added by calling drm_mode_probed_add().

	 * The number of modes added by calling drm_mode_probed_add(). Return 0

	 * on failures (no modes) instead of negative error codes.

	 */

	int (*get_modes)(struct drm_connector *connector);