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

[ Upstream commit 7af03e6887 ]

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: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/50208c866facc33226a3c77b82bb96aeef8ef310.1709913674.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Jani Nikula 2024-03-08 18:03:39 +02:00 committed by Greg Kroah-Hartman
parent b7f6c3630e
commit cb676955d1
2 changed files with 9 additions and 1 deletions

View File

@ -362,6 +362,13 @@ 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.

View File

@ -896,7 +896,8 @@ 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);