[PATCH] drm: Fire off KMS hotplug events if probe detect says the connector is connected

[Daniel Vetter]

On Thu, Apr 18, 2019 at 01:15:17PM +0000, Mun, Gwan-gyeong wrote:
> On Thu, 2019-04-18 at 10:28 +0200, Daniel Vetter wrote:
> > On Thu, Apr 18, 2019 at 11:09:29AM +0300, Gwan-gyeong Mun wrote:
> > > The hotplug detection routine of drm_helper_hpd_irq_event() can
> > > detect
> > > changing of status of connector, but it can not detect changing of
> > > properties of the connector.
> > > e.g. changing of edid while suspend/resume, changing of dp lanes in
> > > dp aux.
> > > 
> > > Following scenario explains one of them; A detection of changing of
> > > edid.
> > > 
> > >  1) plug display device to a connector
> > >  2) system suspend
> > >  3) unplug 1)'s display device and plug the other display device to
> > > a
> > >     connector
> > >  4) system resume
> > > 
> > > To solve explained cases, It fires off KMS hotplug events if
> > > drm_helper_probe_detect() says the connector is connected.
> > > 
> > > Testcase: igt/kms_chamelium/hdmi-edid-change-during-hibernate
> > > Testcase: igt/kms_chamelium/hdmi-edid-change-during-suspend
> > > Testcase: igt/kms_chamelium/dp-edid-change-during-hibernate
> > > Testcase: igt/kms_chamelium/dp-edid-change-during-suspend
> > > 
> > > Suggested-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> > 
> > This isn't at all what I suggested.
> > -Daniel
> Because the code modification was followed by your comments, so I added
> suggested-by line. I will remove this line and will resend it.

Apologies for not being clear: I don't think this here is what we want
really, and it's not what I suggested. I'm not exactly sure why you think
this will work, essentially it just always generates a hotplug uevent for
irq, but totally ignores polling. I guess it works, but that's a hack, not
something we should merge.
-Daniel

> Br,
> G.G.
> > 
> > > Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun at intel.com>
> > > Link: 
> > > https://lists.freedesktop.org/archives/dri-devel/2019-April/214572.html
> > > ---
> > >  drivers/gpu/drm/drm_probe_helper.c | 3 ++-
> > >  1 file changed, 2 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/gpu/drm/drm_probe_helper.c
> > > b/drivers/gpu/drm/drm_probe_helper.c
> > > index 6fd08e04b323..081a849104f2 100644
> > > --- a/drivers/gpu/drm/drm_probe_helper.c
> > > +++ b/drivers/gpu/drm/drm_probe_helper.c
> > > @@ -780,7 +780,8 @@ bool drm_helper_hpd_irq_event(struct drm_device
> > > *dev)
> > >  			      connector->name,
> > >  			      drm_get_connector_status_name(old_status)
> > > ,
> > >  			      drm_get_connector_status_name(connector-
> > > >status));
> > > -		if (old_status != connector->status)
> > > +		if (old_status != connector->status ||
> > > +		    connector->status == connector_status_connected)
> > >  			changed = true;
> > >  	}
> > >  	drm_connector_list_iter_end(&conn_iter);
> > > -- 
> > > 2.21.0
> > > 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch