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

[Alex Deucher]

On Wed, Jan 25, 2017 at 1:32 PM, Harry Wentland <harry.wentland at amd.com> wrote:
> You mean rebase dal/dc on drm-next with these patches?

This is a core MST fix, so it would be good to get upstream for all drivers.

>
> I'll see if I find some time today or tomorrow to do that. We'll
> probably need that anyways for our atomic rework.
>
> Do you still rebase amd-staging on drm-next?
> https://cgit.freedesktop.org/~agd5f/linux/log/?h=amd-staging-drm-next
> looks a few weeks old now.

I haven't had a chance to rebase that branch in quite a while.

Alex

>
> Harry
>
> On 2017-01-25 12:24 PM, Alex Deucher wrote:
>> On Wed, Jan 25, 2017 at 12:16 PM, Krzysztof Nowicki
>> <krzysztof.a.nowicki at gmail.com> wrote:
>>> 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'.
>> Harry,
>>
>> Any chance you could re-spin this against something more recent and re-send?
>>
>> Alex
>