On 7 May 2014 18:07, Daniel Vetter daniel@ffwll.ch 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@chris-wilson.co.uk 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/displaydevicen...
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?
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.
And of course userspace can still check the EDID serial.
I'm going to just add a property with the path and the userspace driver can reconstruct a name from that property, seems like the best plan,
Also for non-DP outputs, you don't know what they are, at least on dock I have I can tell if I have a legacy or a DP device plugged in to a port, but nothing else about it. When nothing is plugged in the port isn't connected.
So on the dock there is a VGA port, HDMI and DP shared, DVI-D and DP shared, I see 3 ports in the MST protocol, until something gets plugged in to something I get no more info.
Dave.