From mboxrd@z Thu Jan 1 00:00:00 1970 From: Aaron Plattner Subject: Re: [RFC] drm + i915 DP MST code preview Date: Wed, 7 May 2014 00:16:37 -0700 Message-ID: <5369DDD5.5010906@nvidia.com> References: <1399005585-2396-1-git-send-email-airlied@gmail.com> <20140502085206.GB21695@nuc-i3427.alporthouse.com> <20140503090028.GB9420@nuc-i3427.alporthouse.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: Received: from hqemgate16.nvidia.com (hqemgate16.nvidia.com [216.228.121.65]) by gabe.freedesktop.org (Postfix) with ESMTP id 0E51F6E49E for ; Wed, 7 May 2014 00:16:39 -0700 (PDT) In-Reply-To: <20140503090028.GB9420@nuc-i3427.alporthouse.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Chris Wilson , Dave Airlie , dri-devel List-Id: dri-devel@lists.freedesktop.org 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 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 -- Aaron