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
>
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