On Tue, 02 Jun 2020 19:18:15 +0000 Simon Ser <contact@xxxxxxxxxxx> wrote: > Describe what a "BAD" link-status means for user-space and how it should > handle it. The logic described has been implemented in igt [1]. > > v2: > > - Change wording to avoid "enabled" (Daniel) > - Add paragraph about multiple connectors sharing the same CRTC (Pekka) > - Add paragraph about performing an atomic commit on a connector without > updating the link-status property (Daniel) > > [1]: https://gitlab.freedesktop.org/drm/igt-gpu-tools/-/commit/fbe61f529737191d0920521946a575bd55f00fbe > > Signed-off-by: Simon Ser <contact@xxxxxxxxxxx> > Cc: Daniel Vetter <daniel@xxxxxxxx> > Cc: Manasi Navare <manasi.d.navare@xxxxxxxxx> > Cc: Pekka Paalanen <ppaalanen@xxxxxxxxx> > --- > drivers/gpu/drm/drm_connector.c | 15 +++++++++++++++ > 1 file changed, 15 insertions(+) > > diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c > index f2b20fd66319..829b21124048 100644 > --- a/drivers/gpu/drm/drm_connector.c > +++ b/drivers/gpu/drm/drm_connector.c > @@ -994,6 +994,21 @@ static const struct drm_prop_enum_list dp_colorspaces[] = { > * after modeset, the kernel driver may set this to "BAD" and issue a > * hotplug uevent. Drivers should update this value using > * drm_connector_set_link_status_property(). > + * > + * When user-space receives the hotplug uevent and detects a "BAD" > + * link-status, the sink doesn't receive pixels anymore. The list of > + * available modes may have changed. User-space is expected to pick a new > + * mode if the current one has disappeared and perform a new modeset with > + * link-status set to "GOOD" to re-enable the connector. > + * > + * If multiple connectors share the same CRTC and one of them gets a "BAD" > + * link-status, the other are unaffected (ie. the sinks still continue to > + * receive pixels). > + * Hi, looks good up to here. > + * When user-space performs an atomic commit on a connector with a "BAD" > + * link-status without resetting the property to "GOOD", it gets > + * implicitly reset. This might make the atomic commit fail if the modeset > + * is unsuccessful. I think this was what Daniel was saying that the kernel should require ALLOW_MODESET to be set for the automatic reset, right? I'm fine with how the doc is written now. But if ALLOW_MODESET becomes a requirement for the automatic reset, I suspect there is a risk to regress Weston, assuming the automatic reset used to be successful. I understand this doc describes the current situation and it answers my questions, so: Acked-by: Pekka Paalanen <pekka.paalanen@xxxxxxxxxxxxx> Thanks, pq > * non_desktop: > * Indicates the output should be ignored for purposes of displaying a > * standard desktop environment or console. This is most likely because
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