[igt-dev] [RFC incomplete PATCH i-g-t] lib/igt_kms: Reduce probing and allow initial hotplug during igt_display_init()

[Pandiyan, Dhinakaran]

On Fri, 2018-03-23 at 14:55 +0100, Maarten Lankhorst wrote:
> Op 23-03-18 om 14:03 schreef Ville Syrjälä:
> > On Fri, Mar 23, 2018 at 01:48:28PM +0100, Maarten Lankhorst wrote:
> >> When booting with fbdev disabled, all outputs are set to UNKNOWNCONNECTION.
> >> In this case we have to reprobe, but in all others we can safely assume that
> >> the output connector status is valid.
> >>
> >> Enumerate all outputs, and for good measure recheck after we probed, to add
> >> and DP-MST we may have missed.
> >>
> >> Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> >> Cc: Lyude <lyude at redhat.com>
> >> Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
> >> ---
> >> Unfortunately we lack a way to determine whether the probing will enumerate
> >> additional DP-MST displays, so the only way right now to test DP-MST would be
> >> to add a sleep(5) in igt_display_check_hotplug.
> >>
> >> Any thoughts how we can make this more reliable for DP-MST?
> > When do we fill out the debugfs mst topology information?
> I have no idea..
> 
> drm_dp_mst_link_probe_work seems to be called from irq, I don't think we initially do discovery, maybe we should..

Correct me if I am wrong.

getconnector->fill_modes->detect->long_pulse->intel_dp_configure_mst->drm_dp_mst_link_probe_work should lead to
/sys/kernel/debug/dri/0/i915_dp_mst_info populating the status of downstream connectors.

Isn't it possible to wait on that?