On 05/07/2014 01:07 AM, Daniel Vetter wrote:
On Wed, May 07, 2014 at 12:16:37AM -0700, Aaron Plattner wrote:
On 05/03/2014 02:00 AM, Chris Wilson wrote:
On Sat, May 03, 2014 at 07:08:02AM +1000, Dave Airlie wrote:
On 2 May 2014 18:52, Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote:
On Fri, May 02, 2014 at 02:39:37PM +1000, Dave Airlie wrote:
the GUID is only on DP 1.2 devices, so you don't get one for ever
port, also GUIDs are wiped on powerdown on most devices, default GUID
is 0 except where devices have USB hubs as well, so it probably
doesn't make much sense to bother exposing them directly.
Ok. It looks like if we do attempt to maintain persistent naming, we need
to do it in the kernel anyway. That is to make sure that a downstream
device always has the same type-id upon reconnection - at least for the
lifetime of module. Or maybe the output name is irrelevant for
preserving extended desktop configurations?
Dunno if it helps, but for roughly similar reasons we ended up naming the
outputs based on their topology paths in the NVIDIA driver. So for example
a port named DP-3 that has a Dell UP2414Q attached will show up as two
outputs named DP-3.1 and DP-3.8 since its internal bridge uses downstream
ports 1 and 8. This has worked out fairly well in practice.
Here's how I described it in the README:
When DisplayPort 1.2 branch devices are present, display
devices will be created with type- and connector-based names
that are based on how they are connected to the branch device
tree. For example, if a connector named DP-2 has a branch
device attached and a DisplayPort device is connected to the
branch device's first downstream port, a display device named
DP-2.1 might be created. If another branch device is
connected between the first branch device and the display
device, the name might be DP-2.1.1.
To avoid cluttering the output list, DisplayPort 1.2 devices
can be deleted when they are no longer connected and are not
named in any MetaModes. This behavior can be enabled with the
DeleteUnusedDP12Displays option.
http://us.download.nvidia.com/XFree86/Linux-x86/337.19/README/displaydevicenames.html
I'm unclear how you name non-DP branch devices. Do they show up as
DP-2.1-HDMI or something similar? Or do you just keep the DP-2.1 name but
set the connector type to HDMI?
I don't have any branches that support passive adapters on downstream
ports, so I'm not sure what happens with those.
In general I think your prosoal of adding branch downstream ports to name
MST connectors sounds really good. The kms object ids will still be
random, but at least if users connect the same topology to the same ports
we should have stable names.
Yeah, the RandR output XIDs work the same way.
And of course userspace can still check the EDID serial.
-Daniel
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