[PATCH 3/5] drm/dp/mst: change MST detection scheme

[Krzysztof Nowicki]

Hi,

On środa, 15 czerwca 2016 14:14:01 CET  wrote:
> On 15 June 2016 at 13:49, Dave Airlie <airlied at gmail.com> wrote:
> > Excuse me for top posting.
> > 
> > So I finally got back to this patch, still don't like it.
> > 
> > Apart from the doing 3 things in once which is just annoying, current
> > userspace for tiled monitors
> > relies on the behaviour that the cached edids are retrieved before the
> > connector is show to userspace.
> > 
> > This is so that for tiled monitors both connectors are shown with
> > tiling properties so userspace can pick the correct monitor size.
> > 
> > Now I realise this isn't great, since at least for the two cable 5K
> > monitors you won't ever plug them in at once.
> > 
> > So we should probably discuss more what userspace should do in the
> > presence of a tiled monitor where it can only see one tile,
> > 
> > If we go ahead with something like this, things will look kinda ugly
> > as you plug in a 4k monitor and it'll try and set a mode
> > on the first tile when it gets the hotplug (or it could be racing and
> > notice the connectors before the hotplug). So it then
> > sets the 1920x1080 mode on one connector and gets another hotplug to
> > set the tiled mode up.
> 
> Though I think the fix is to leave the cached edid test in add port,
> 
> And maybe the rest of the patch is okay then.
> 
> Dave.

Is this patch still being considered for pulling in?

Recently I've been fighting with a HP UltraSlim docking station with a MST hub 
inside in order to get it working with the amdgpu DAL/DC code. I couldn't get 
it to work until I stumbled upon this patch. Applying it solved the issue 
instantly.

What I have found during debugging is that the MST hub would return SST sink 
port numbers < 8 which resulted in no EDID being retrieved and in turn the 
status of the outputs was 'disconnected'.

Regards
Chris