From eb47fe8033d6c2013ce47ec44f39fa0092aa8551 Mon Sep 17 00:00:00 2001 From: Thierry Reding Date: Mon, 16 Nov 2015 18:19:53 +0100 Subject: drm: Do not set connector->encoder in drivers An encoder is associated with a connector by the DRM core as a result of setting up a configuration. Drivers using the atomic or legacy helpers should never set up this link, even if it is a static one. While at it, try to catch this kind of error in the future by adding a WARN_ON() in drm_mode_connector_attach_encoder(). Note that this doesn't cover all the cases, since drivers could set this up after attaching. Drivers that use the atomic helpers will get a warning later on, though, so hopefully the two combined cover enough to help people avoid this in the future. Cc: Russell King Cc: Philipp Zabel Cc: Laurent Pinchart Cc: Liviu Dudau Cc: Mark yao Signed-off-by: Thierry Reding Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/1447694393-24700-1-git-send-email-thierry.reding@gmail.com --- drivers/gpu/drm/drm_crtc.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'drivers/gpu/drm/drm_crtc.c') diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c index 62fa95fa5471..d40bab29747e 100644 --- a/drivers/gpu/drm/drm_crtc.c +++ b/drivers/gpu/drm/drm_crtc.c @@ -5054,6 +5054,20 @@ int drm_mode_connector_attach_encoder(struct drm_connector *connector, { int i; + /* + * In the past, drivers have attempted to model the static association + * of connector to encoder in simple connector/encoder devices using a + * direct assignment of connector->encoder = encoder. This connection + * is a logical one and the responsibility of the core, so drivers are + * expected not to mess with this. + * + * Note that the error return should've been enough here, but a large + * majority of drivers ignores the return value, so add in a big WARN + * to get people's attention. + */ + if (WARN_ON(connector->encoder)) + return -EINVAL; + for (i = 0; i < DRM_CONNECTOR_MAX_ENCODER; i++) { if (connector->encoder_ids[i] == 0) { connector->encoder_ids[i] = encoder->base.id; -- cgit v1.2.3