Re: [igt-dev] [PATCH] tests/kms_dp_aux_dev: Handle AUX failures on disconnected MST connectors

[Imre Deak <imre.deak@intel.com>]

On Tue, Oct 13, 2020 at 02:27:12PM +0300, Ville Syrjälä wrote:
> On Mon, Oct 12, 2020 at 08:56:54PM +0300, Imre Deak wrote:
> > The DPCD of an MST connector is read out with a REMOTE_DPCD_READ MST
> > request. If the given connector is disconnected this read will result in
> > an MST NAK reply and this will be reported as an EIO error to the
> > initiator of the AUX read.
> > 
> > Handle this in the test that attempts to read the DPCD of any exposed
> > connector, whether they are connected or not.
> 
> MST connectors get nuked once disconnected no? So is this just to avoid
> some race with the connector disappearing during the test?

During enumeration of the ports of an MSTB (in response to a hotplug
when at least one port is connected) a connector is added for all
(output) ports, even if they are not connected. If a port gets unplugged
the connector is removed yes, but a new connector for this port is added
back since the parent MSTB is reprobed then.

> 
> > 
> > Signed-off-by: Imre Deak <imre.deak@intel.com>
> > ---
> >  tests/kms_dp_aux_dev.c | 16 +++++++++++++---
> >  1 file changed, 13 insertions(+), 3 deletions(-)
> > 
> > diff --git a/tests/kms_dp_aux_dev.c b/tests/kms_dp_aux_dev.c
> > index 4f52434a..39fc2b92 100644
> > --- a/tests/kms_dp_aux_dev.c
> > +++ b/tests/kms_dp_aux_dev.c
> > @@ -34,6 +34,14 @@
> >  
> >  IGT_TEST_DESCRIPTION("Test that /dev/drm_dp_aux reads work");
> >  
> > +static bool is_mst_connector(int drm_fd, uint32_t connector_id)
> > +{
> > +	return kmstest_get_property(drm_fd, connector_id,
> > +				    DRM_MODE_OBJECT_CONNECTOR,
> > +				    "PATH", NULL,
> > +				    NULL, NULL);
> > +}
> > +
> >  static bool test(int drm_fd, uint32_t connector_id)
> >  {
> >  	drmModeConnector *connector;
> > @@ -67,10 +75,12 @@ static bool test(int drm_fd, uint32_t connector_id)
> >  		igt_assert(fd >= 0);
> >  
> >  		ret = read(fd, buf, sizeof(buf));
> > -		igt_assert(ret == sizeof(buf) || errno == ETIMEDOUT);
> > -
> >  		igt_info("%s: %s\n", path,
> > -			 ret > 0 ? "success" : "timed out");
> > +			 ret > 0 ? "success" : strerror(errno));
> > +
> > +		igt_assert(ret == sizeof(buf) ||
> > +			   errno == ETIMEDOUT ||
> > +			   (errno == EIO && is_mst_connector(drm_fd, connector_id)));
> >  
> >  		close(fd);
> >  
> > -- 
> > 2.20.1
> > 
> > _______________________________________________
> > igt-dev mailing list
> > igt-dev@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/igt-dev
> 
> -- 
> Ville Syrjälä
> Intel
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