On Mon, Sep 17, 2018 at 05:12:04PM -0400, Lyude Paul wrote:
> On Mon, 2018-09-17 at 21:16 +0300, Ville Syrjälä wrote:
> > On Mon, Sep 17, 2018 at 02:10:02PM -0400, Lyude Paul wrote:
> > > On Mon, 2018-09-17 at 20:55 +0300, Ville Syrjälä wrote:
> > > > On Mon, Sep 17, 2018 at 01:43:44PM -0400, Lyude Paul wrote:
> > > > > Userspace asked them to be forced off, so why would we care about what a
> > > > > probe tells us?
> > > >
> > > > I believe there should be force checks in the callers already.
> > > > Or are we missing some?
> > >
> > > JFYI, what triggered me to send this patch are these error messages that
> > > come
> > > from nouveau when a hotplug happens on a port that we've forced off:
> > >
> > > [ 1903.918104] nouveau 0000:01:00.0: DRM: DDC responded, but no EDID for DP-
> > > 2
> > > [ 1903.918123] [drm:drm_helper_hpd_irq_event [drm_kms_helper]]
> > > [CONNECTOR:61:DP-2] status updated from disconnected to disconnected
> > >
> > > That being said; I'm sure there are probably some checks missing, but I
> > > don't
> > > really see the purpose in calling the driver's probe functions at all if
> > > they're
> > > just supposed to return the status we forced.
> >
> > Digging through my cobweb ridden local git repository I found this:
> >
> > commit bbd17813a7c7d0210c619365707044d0fb29e3f0
> > Author: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> > Date: Mon Jun 10 15:28:55 2013 +0300
> >
> > drm: Ignore forced connectors in drm_helper_hpd_irq_event()
> >
> > drm_helper_hpd_irq_event() calls the connector's .detect() function
> > even for forced connectors. If the returned status doesn't match the
> > forced status, we will send the hotplug event, causing userspace to
> > re-probe all the connectors. Eventually we should end up back where
> > we started when drm_helper_probe_single_connector_modes() overwrites
> > the connector status with the forced status.
> >
> > We can avoid all that pointles work if we just skip forced connectors
> > in drm_helper_hpd_irq_event().
> >
> > Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> >
> > diff --git a/drivers/gpu/drm/drm_crtc_helper.c
> > b/drivers/gpu/drm/drm_crtc_helper.c
> > index ed1334e27c33..4fc2ad76c107 100644
> > --- a/drivers/gpu/drm/drm_crtc_helper.c
> > +++ b/drivers/gpu/drm/drm_crtc_helper.c
> > @@ -1086,6 +1086,10 @@ void drm_helper_hpd_irq_event(struct drm_device *dev)
> > mutex_lock(&dev->mode_config.mutex);
> > list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
> >
> > + /* Ignore forced connectors. */
> > + if (connector->force)
> > + continue;
> > +
> > /* Only handle HPD capable connectors. */
> > if (!(connector->polled & DRM_CONNECTOR_POLL_HPD))
> > continue;
> >
> >
> > I guess I never sent it out.
>
> Ahhh, to be honest though this patch isn't really enough.
> drm_helper_hpd_irq_event() isn't going to be used by all drivers (I may remove
> some usage of it in nouveau in the near future, even) so I still think it would
> be a better idea to just add this into drm_helper_probe_detect() and
> drm_helper_probe_detect_ctx() so everything gets covered
Atm all connector->force handling is outside of drm_helper_probe_detect. I
guess we could try to push (some) of it into this helper, if that's
useful. There seems to be some duplication already. But adding a redundant
check like you do here feels a bit funky. Maybe makes more sense in
context of the nouveau stuff you're working on?
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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