Re: [igt-dev] [PATCH i-g-t v2] tests/kms_chamelium: Make sure we wait for each connectors' hotplug event

Paul Kocialkowski
2019-05-09T12:24:30Z

Hi,

On Thu, 2019-05-09 at 15:08 +0300, Imre Deak wrote:
> On Thu, May 09, 2019 at 09:25:41AM +0200, Paul Kocialkowski wrote:
> > On Wed, 2019-05-08 at 11:24 +0300, Imre Deak wrote:
> > > After scheduling an HPD toggle event, make sure that we wait for the
> > > hotplug event for each connector that may be sent by the driver.
> > >
> > > Depending on the scheduling there could be 1 event or as many events as
> > > connectors we scheduled an HPD toggle event on, depending on the timing.
> > > So if we don't yet see the expected connector state on a given connector
> > > try to wait for an additional hotplug event and reprobe/recheck the
> > > state.
> >
> > This changes makes good sense to me, so:
> >
> > Reviewed-By: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> >
> > And it brings back hard feelings about the hotplug interface we have
> > today...
>
> Yes, I was surprised too not find any way to identify which connector(s)
> the hotplug event is associated with. We discussed with Ville if it'd
> make sense to add a connector ID map to the uevent, but not sure if it'd
> be useful outside of this test, or how that would align with Chris'
> connector probe state generation idea.

Either way, I'm definitely in favor of having something more reliable
to expose to userspace. Having something to correlate each event to one
(or more) connector(s) sounds good to me.

And I think there is a general need for this, it's not just IGT.

Currently, every userspace application using DRM has to do a full
reprobe once a hotplug uevent is received, which is really not optimal.
If an entry identifying the connector was also provided, userspace
could only reprobe that connector. The step after that would be having
the indication of whether the connector was connected or disconnected
directly in uevent too, so that no probing needs to be done at all when
a given connector is disconnected.

Anyway, if you're interested in the idea and that Ville and Chris are
in favor, I really think it would be worth fixing that. And we'd only
be adding new elements to uevent, so that would stay backward-
compatible too.

Cheers,

Paul

> > > v2:
> > > - s/igt_assert(x >= y)/igt_assert_lte(y, x)/ to see the actual limits in
> > > the debugging output. (Lyude)
> > >
> > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=110534
> > > Cc: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> > > Cc: Lyude Paul <lyude@redhat.com>
> > > Signed-off-by: Imre Deak <imre.deak@intel.com>
> > > Reviewed-by: Lyude Paul <lyude@redhat.com>
> > > ---
> > > tests/kms_chamelium.c | 45 +++++++++++++++++++++++++++++++++++++------
> > > 1 file changed, 39 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/tests/kms_chamelium.c b/tests/kms_chamelium.c
> > > index 714e5e06..502f1efa 100644
> > > --- a/tests/kms_chamelium.c
> > > +++ b/tests/kms_chamelium.c
> > > @@ -284,11 +284,32 @@ test_edid_read(data_t *data, struct chamelium_port *port,
> > > drmModeFreeConnector(connector);
> > > }
> > >
> > > +/* Wait for hotplug and return the remaining time left from timeout */
> > > +static bool wait_for_hotplug(struct udev_monitor *mon, int *timeout)
> > > +{
> > > + struct timespec start, end;
> > > + int elapsed;
> > > + bool detected;
> > > +
> > > + igt_assert_eq(igt_gettime(&start), 0);
> > > + detected = igt_hotplug_detected(mon, *timeout);
> > > + igt_assert_eq(igt_gettime(&end), 0);
> > > +
> > > + elapsed = igt_time_elapsed(&start, &end);
> > > + igt_assert_lte(0, elapsed);
> > > + *timeout = max(0, *timeout - elapsed);
> > > +
> > > + return detected;
> > > +}
> > > +
> > > static void
> > > try_suspend_resume_hpd(data_t *data, struct chamelium_port *port,
> > > enum igt_suspend_state state, enum igt_suspend_test test,
> > > struct udev_monitor *mon, bool connected)
> > > {
> > > + drmModeConnection target_state = connected ? DRM_MODE_DISCONNECTED :
> > > + DRM_MODE_CONNECTED;
> > > + int timeout = HOTPLUG_TIMEOUT;
> > > int delay;
> > > int p;
> > >
> > > @@ -310,17 +331,29 @@ try_suspend_resume_hpd(data_t *data, struct chamelium_port *port,
> > > }
> > >
> > > igt_system_suspend_autoresume(state, test);
> > > + igt_assert(wait_for_hotplug(mon, &timeout));
> > >
> > > - igt_assert(igt_hotplug_detected(mon, HOTPLUG_TIMEOUT));
> > > if (port) {
> > > - igt_assert_eq(reprobe_connector(data, port), connected ?
> > > - DRM_MODE_DISCONNECTED : DRM_MODE_CONNECTED);
> > > + igt_assert_eq(reprobe_connector(data, port), target_state);
> > > } else {
> > > for (p = 0; p < data->port_count; p++) {
> > > + drmModeConnection current_state;
> > > +
> > > port = data->ports[p];
> > > - igt_assert_eq(reprobe_connector(data, port), connected ?
> > > - DRM_MODE_DISCONNECTED :
> > > - DRM_MODE_CONNECTED);
> > > + /*
> > > + * There could be as many hotplug events sent by
> > > + * driver as connectors we scheduled an HPD toggle on
> > > + * above, depending on timing. So if we're not seeing
> > > + * the expected connector state try to wait for an HPD
> > > + * event for each connector/port.
> > > + */
> > > + current_state = reprobe_connector(data, port);
> > > + if (p > 0 && current_state != target_state) {
> > > + igt_assert(wait_for_hotplug(mon, &timeout));
> > > + current_state = reprobe_connector(data, port);
> > > + }
> > > +
> > > + igt_assert_eq(current_state, target_state);
> > > }
> > >
> > > port = NULL;
> > --
> > Paul Kocialkowski, Bootlin
> > Embedded Linux and kernel engineering
> > https://bootlin.com
> >
--
Paul Kocialkowski, Bootlin
Embedded Linux and kernel engineering