On Fri, May 22, 2015 at 10:54:12AM +0100, Chris Wilson wrote: > On Fri, May 22, 2015 at 12:03:27PM +0300, Ville Syrjälä wrote: > > On Mon, Apr 20, 2015 at 02:28:56PM +0100, Chris Wilson wrote: > > > The intention of using video=<connector>:<mode> is primarily to select > > > the user's preferred resolution at startup. Currently we always create a > > > new mode irrespective of whether the monitor has a native mode at the > > > desired resolution. This has the issue that we may then select the fake > > > mode rather the native mode during fb_helper->inital_config() and so > > > if the fake mode is invalid we then end up with a loss of signal. Oops. > > > This invalid fake mode would also be exported to userspace, who > > > potentially may make the same mistake. > > > > > > To avoid this issue, we filter out the added command line mode if we > > > detect the desired resolution (and clock if specified) amongst the > > > probed modes. This fixes the immediate problem of adding a duplicate > > > mode, but perhaps more generically we should avoid adding a GTF mode if > > > the monitor has an EDID that is not GTF-compatible, or similarly for > > > CVT. > > > > > > A second issue sneaked into this patch is to add the cmdline mode mode > > > ahead of the absolute fallback 1024x768 mode. That is if the user has > > > specified a mode that we create as a fallback, we do not need to add a > > > second unused fallback mode. > > > > > > Fixes regression from > > > > > > commit eaf99c749d43ae74ac7ffece5512f3c73f01dfd2 > > > Author: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > > Date: Wed Aug 6 10:08:32 2014 +0200 > > > > > > drm: Perform cmdline mode parsing during connector initialisation > > > > > > that breaks HDMI output on BeagleBone Black with LG TV (model 19LS4R-ZA). > > > > > > v2: Explicitly delete our earlier cmdline mode > > > > > > Reported-by: Radek Dostál <rd@xxxxxxxxxxxxxxx> > > > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > > Cc: Radek Dostál <rd@xxxxxxxxxxxxxxx> > > > Cc: Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx> > > > Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > > > Cc: Daniel Vetter <daniel.vetter@xxxxxxxx> > > > Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx > > > Cc: Julia Lemire <jlemire@xxxxxxxxxx> > > > Cc: Dave Airlie <airlied@xxxxxxxxxx> > > > Cc: stable@xxxxxxxxxxxxxxx > > > --- > > > drivers/gpu/drm/drm_modes.c | 2 +- > > > drivers/gpu/drm/drm_probe_helper.c | 39 +++++++++++++++++++++++++++++++++++--- > > > 2 files changed, 37 insertions(+), 4 deletions(-) > > > > > > diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c > > > index 213b11ea69b5..13293e009990 100644 > > > --- a/drivers/gpu/drm/drm_modes.c > > > +++ b/drivers/gpu/drm/drm_modes.c > > > @@ -1400,7 +1400,7 @@ drm_mode_create_from_cmdline_mode(struct drm_device *dev, > > > if (!mode) > > > return NULL; > > > > > > - mode->type |= DRM_MODE_TYPE_USERDEF; > > > + mode->type |= DRM_MODE_TYPE_USERDEF | DRM_MODE_TYPE_DRIVER; > > > > Why do we need the DRIVER flag here? > > So we can differentiate it from an equivalent mode added by the user > later on. Users can't actually add modes to the connector mode list. > > > > + /* Remove the existing fake mode */ > > > + list_for_each_entry(mode, &connector->modes, head) { > > > + if ((mode->type & (DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_USERDEF)) != (DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_USERDEF)) > > > + continue; > > > > Doesn't drm_mode_connector_list_update() kill it from the list > > eventually if there's no matching mode present on the > > probed_modes list? > > Hmm, that's what I thought I tried at first. If I remember correctly we > had to set mode->status in order to prune it since > drm_mode_connector_list_update() itself doesn't do the deletion. Using > the mode->status was problematic, and the simplest way to do delete the > original cmdline mode was by explicitly removing it ourselves. Oh right drm_mode_connector_list_update() only removes the duplicates. And the the mode->status handling is a bit strange. Not helped by the fact that MODE_OK is zero so all kzalloced modes start out as MODE_OK. While I was doing the mode santiy check stuff I did consider that I should change new modes to be MODE_UNVERIFIED by default, but I was feeling lazy and decided against it in the end. So yeah getting the normal prune mechanism to kill the mode would required some rework to the mode status->handling probably, so seems like a somewhat bigger effort. > > > > @@ -179,9 +212,9 @@ static int drm_helper_probe_single_connector_modes_merge_bits(struct drm_connect > > > count = (*connector_funcs->get_modes)(connector); > > > } > > > > > > + count += drm_helper_probe_add_cmdline_mode(connector); > > > if (count == 0 && connector->status == connector_status_connected) > > > count = drm_add_modes_noedid(connector, 1024, 768); > > > - count += drm_helper_probe_add_cmdline_mode(connector); > > > > Hmm. This means drm_add_modes_noedid() will never be called if the > > cmdline mode is present, and hence the mode list will only ever have > > that single mode user specified mode. Not sure if that can be considered > > a real problem or not. > > I consider it to a real problem as it goes against my expectations as a > user, that is if I specify a mode to use, I expect that mode to be used. > Doesn't need to be in this patch though. Yeah, I was just thinking it might be nice to have the other dmt modes still be on the list. But I don't really mind at this time since I try to avoid cables that don't connect the ddc pins. -- Ville Syrjälä Intel OTC -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html