On Wed, Aug 02, 2017 at 01:49:18AM +0000, Pandiyan, Dhinakaran wrote:
>
> On Tue, 2017-08-01 at 16:51 +0800, Ethan Hsieh wrote:
> > We do not update the status of connector when receiving MST unplug event.
> > Call detect function to get latest status and then update status of
> > connector.
> >
>
> Cc'ing Daniel and Chris.
>
> Thanks for sending this to the list.
>
> The issue is connector ref count is not zero when
> destroy_mst_connector() is called, which results in the connector not
> being freed until the userspace shuts down the crtc tied to the
> connector. But the kernel needs to update the connector status for the
> user space to shut it down.
Here's what's supposed to happen:
1. kernel sends out uevent
2. userspace does a full probe using GetConnector
3. kernel calls down into ->probe, updates connector->status
4. userspace notices the connector is disconnected, shuts down the
CRTC/connector pipe
5. Last reference is dropped, connector disappears
6. Another round of uevent for the kernel removal (I think, not sure about
this one).
I suspect your userspace fails to do 2 if you need this patch.
-Daniel
>
>
> > Before applying the patch:
> > [313.665321] [drm:intel_get_hpd_pins [i915]] hotplug event received, stat
> > 0x00200000, dig 0x10101012, pins 0x00000020
> > [313.665383] [drm:intel_hpd_irq_handler [i915]] digital hpd port B - long
> > [313.665436] [drm:intel_hpd_irq_handler [i915]] Received HPD interrupt on
> > PIN 5 - cnt: 0
> > [313.665539] [drm:intel_dp_hpd_pulse [i915]] got hpd irq on port B - long
> > [313.944743] [drm:intel_dp_destroy_mst_connector [i915]]
> > [313.944848] [drm:intel_dp_destroy_mst_connector [i915]]
> >
> > After applying the patch:
> > [43.175798] [drm:intel_dp_destroy_mst_connector [i915]] [CONNECTOR:70:DP-4]
> > status updated from connected to disconnected
> > [43.175870] [drm:intel_dp_destroy_mst_connector [i915]]
> > [43.177675] [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]]
> > [CONNECTOR:70:DP-4]
> > [43.177679] [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]]
> > [CONNECTOR:70:DP-4] disconnected
> >
> > Signed-off-by: Ethan Hsieh <ethan.hs...@canonical.com>
>
>
> This patch needs a Fixes: tag as it does fix a fdo bug.
>
>
> > ---
> > drivers/gpu/drm/i915/intel_dp_mst.c | 14 ++++++++++++++
> > 1 file changed, 14 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c
> > b/drivers/gpu/drm/i915/intel_dp_mst.c
> > index e4ea968..b02a9a8 100644
> > --- a/drivers/gpu/drm/i915/intel_dp_mst.c
> > +++ b/drivers/gpu/drm/i915/intel_dp_mst.c
> > @@ -492,6 +492,20 @@ static void intel_dp_destroy_mst_connector(struct
> > drm_dp_mst_topology_mgr *mgr,
> > {
> > struct intel_connector *intel_connector = to_intel_connector(connector);
> > struct drm_i915_private *dev_priv = to_i915(connector->dev);
> > + enum drm_connector_status old_status;
> > +
> > + mutex_lock(&connector->dev->mode_config.mutex);
> > + old_status = connector->status;
> > + connector->status = connector->funcs->detect(connector, false);
>
> Isn't detect already done by this point? destroy_connector() should be
> called after we know the display is disconnected.
>
> > +
> > + if (old_status != connector->status)
> > + DRM_DEBUG_KMS("[CONNECTOR:%d:%s] status updated from %s to
> > %s\n",
> > + connector->base.id,
> > + connector->name,
> > + drm_get_connector_status_name(old_status),
> > + drm_get_connector_status_name(connector->status));
> > +
> > + mutex_unlock(&connector->dev->mode_config.mutex);
> >
> > drm_connector_unregister(connector);
>
> The connector is unregistered unconditionally here, so you might as well
> set
> connector->status = connector_status_disconnected;
>
> >
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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