[igt-dev] [PATCH] lib/chamelium: Support MST connectors on reprobe by using connector name
Mark Yacoub
markyacoub at chromium.org
Mon Aug 15 19:54:07 UTC 2022
Updated in Patch 2: https://patchwork.freedesktop.org/patch/497791/
Thank you!
On Mon, Aug 1, 2022 at 4:03 PM Lyude Paul <lyude at redhat.com> wrote:
>
> On Wed, 2022-07-27 at 15:37 -0400, Mark Yacoub wrote:
> > On Tue, Jul 26, 2022 at 7:26 PM Lyude Paul <lyude at redhat.com> wrote:
> > >
> > > To make sure I'm understanding this code correctly: it seems like we're
> > > looking for a downstream MST port by just checking to see if there's an
> > > identically named port connected?
> > So, what's happening here is that the DUT and Chamelium are required
> > to be in static condition, meaning the same ports are always connected
> > at all times.
> > Before we run any chamelium test, we set up the igt config and
> > specifically match the connected ports as shown in this doc:
> > https://gitlab.freedesktop.org/drm/igt-gpu-tools/-/blob/1b5f7f139660ac27f3c8b4c4a2d23fdd9430ccab/docs/chamelium.txt#L112
> > Through my testing, i saw that even when the connectors were unplugged
> > and disappeared, the connector name assigned in igtrc remained the
> > same, hence my assumption.
> > Given this situation, let me know if my assumption can still hold true.
>
> Heads up: when I say "real connector" here I mean "a physical connector
> directly on the DUT", and when I say "port connectors" I mean any connector in
> an MST topology.
>
> Anyway - that assumption doesn't hold true unfortunately. Connector names are
> totally arbitrary and can change based on the order in which the connectors
> are created, which could change due to any number of factors out of our
> control. For instance, if one MST hub doesn't have a consistent time between
> power on and being available for probing in the topology - you might observe
> the name for that port connector changing between reprobes.
>
> Real connectors on the other hand, should mostly* have the same connector name
> since they're always present on the system. Since those names are consistent
> enough, what you need to do in order to distinguish different port connectors
> is to use the PATH property on the connector in order to figure out the actual
> real connector the port connector is on along with the RAD (relative address,
> e.g. the actual hardware address used to refer to the branch connector). If a
> connector has the same RAD as a previous connector, then they're guaranteed to
> be the same connector. And since the RAD is determined by a branch's location
> in the topology, it'll remain consistent.
>
> * I said mostly because I _THINK_ this assumption may not hold true in certain
> situations when it comes to laptops with multiple GPUs being probed in a
> inconsistent order. You're probably not dealing with that though, so feel free
> to ignore this tidbit :).
>
> > >
> > > That's unfortunately not very reliable because connector names can change
> > > as
> > > well, although the names of connectors that are built into the system
> > > shouldn't. What we could -possibly- do is go through connector's path
> > > properties, and see if they match the previous connector props of the MST
> > > port.
> > >
> > > If this isn't good enough still, then we probably should add a better
> > > connector prop to the kernel then the path prop - preferably one that uses
> > > a
> > > format like this:
> > >
> > > ${CONN_NAME}-${MST_RAD}
> > >
> > > On Wed, 2022-07-20 at 11:19 -0400, Mark Yacoub wrote:
> > > > [Why]
> > > > On unplug, a lone MST connector can become invalid and disappear from
> > > > the list of DRM connectors.
> > > > When this happens, we can't check for the connector ID as it's no longer
> > > > there to check.
> > > > Hence, a connector disappearance indicates a disconnect.
> > > >
> > > > Furthermore, on a replug, the connector ID can change as well. The only
> > > > thing that remains unchageable is the connector name.
> > > >
> > > > [How]
> > > > Do not check for connector connetion state using the connector ID.
> > > > Iterate through the current connectors and match with the name.
> > > > If a connector disappeared, this means it's now disconnected.
> > > > If it's there, return its connection status.
> > > > Update the port connector ID with the current connector ID in case it
> > > > changed on a replug.
> > > >
> > > > Tested on Volteer with Chamelium V3 connected via a 2-DP-port
> > > > CableMatters
> > > > hub.
> > > > Test: kms_chamelium --run-subtest dp-hpd
> > > >
> > > > Signed-off-by: Mark Yacoub <markyacoub at chromium.org>
> > > > ---
> > > > lib/igt_chamelium.c | 52 +++++++++++++++++++++++++++++++++++++++------
> > > > 1 file changed, 45 insertions(+), 7 deletions(-)
> > > >
> > > > diff --git a/lib/igt_chamelium.c b/lib/igt_chamelium.c
> > > > index d78ddd61..b5e9bbfd 100644
> > > > --- a/lib/igt_chamelium.c
> > > > +++ b/lib/igt_chamelium.c
> > > > @@ -266,21 +266,59 @@ chamelium_reprobe_connector(igt_display_t
> > > > *display,
> > > > struct chamelium_port *port)
> > > > {
> > > > drmModeConnector *connector;
> > > > - drmModeConnection status;
> > > > + drmModeConnection connection_status;
> > > > igt_output_t *output;
> > > > + drmModeRes* res = drmModeGetResources(display->drm_fd);
> > > > + bool is_connector_found = false;
> > > > + int i;
> > > >
> > > > igt_debug("Reprobing %s...\n", chamelium_port_get_name(port));
> > > > - connector = chamelium_port_get_connector(chamelium, port, true);
> > > > + for (i = 0; i < res->count_connectors; ++i) {
> > > > + connector = drmModeGetConnector(display->drm_fd, res-
> > > > > connectors[i]);
> > > > + /* If the connector is MST and is now unplugged, the
> > > > spawned
> > > > connectors will no
> > > > + longer be available but can still be counted as part
> > > > of
> > > > res->count_connectors */
> > > > + if (!connector) {
> > > > + drmModeFreeConnector(connector);
> > > > + connector = NULL;
> > > > + continue;
> > > > + }
> > > > +
> > > > + char connector_name[50];
> > > > + snprintf(connector_name, 50, "%s-%u",
> > > > + kmstest_connector_type_str(connector-
> > > > > connector_type),
> > > > + connector->connector_type_id);
> > > > + if (strcmp(connector_name, port->name) == 0) {
> > > > + is_connector_found = true;
> > > > + break;
> > > > + }
> > > > +
> > > > + drmModeFreeConnector(connector);
> > > > + connector = NULL;
> > > > + }
> > > > + drmModeFreeResources(res);
> > > > +
> > > > + if (!is_connector_found) {
> > > > + igt_debug("Connector is not found. This indicates it's
> > > > disconnected.\n");
> > > > + igt_assert(!connector);
> > > > + return DRM_MODE_DISCONNECTED;
> > > > + }
> > > > +
> > > > igt_assert(connector);
> > > > - status = connector->connection;
> > > > + connection_status = connector->connection;
> > > >
> > > > - /* let's make sure that igt_display is up to date too */
> > > > + /* If we still have a connector, let's make sure that
> > > > igt_display
> > > > and the port are up to date too */
> > > > output = igt_output_from_connector(display, connector);
> > > > - output->force_reprobe = true;
> > > > - igt_output_refresh(output);
> > > > + if (output) {
> > > > + output->force_reprobe = true;
> > > > + igt_output_refresh(output);
> > > > + }
> > > > +
> > > > + /* If the topology of the connector is MST, the connector ID
> > > > could
> > > > have changed. Update the
> > > > + chamelium port to the current connector ID. */
> > > > + port->connector_id = connector->connector_id;
> > > >
> > > > drmModeFreeConnector(connector);
> > > > - return status;
> > > > + return connection_status;
> > > > }
> > > >
> > > > /**
> > >
> > > --
> > > Cheers,
> > > Lyude Paul (she/her)
> > > Software Engineer at Red Hat
> > >
> >
>
> --
> Cheers,
> Lyude Paul (she/her)
> Software Engineer at Red Hat
>
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