Re: patch for video.c driver

Matthew Garrett
2009-03-13T17:47:34Z

On Fri, Mar 13, 2009 at 12:36:04PM -0500, Terence Ripperda wrote:

> in the case I'm trying to fix here, a vendor is using the NVIF ACPI
> extensions, rather than the DGS/DCS methods. not all vendors use these, but for
> the ones that do, there's no other way to get the hotkey information. our fix
> here is to update the video.c driver to acknowledge the NVIF methods and pass
> the methods on to the userspace daemon.

I'm not quite clear on what you mean by the hotkey information here. As
far as I'm aware, we don't use DCS/DGS support for anything on Linux
since it often seems to be either broken or just filled with incorrect
information.

> currently the nvidia X driver handles the control logic and display change
> actions on our boards. this was written a couple of years ago and due to nothing
> else in place at the time. we'd prefer to switch to a more generic mechanism in
> line with what the community is working on. my understanding is that there is
> work on a daemon that relies on X RandR 1.2. I would like nvidia to get involved
> in and support that effort. (and I admit nvidia is behind on getting our X RandR
> support up to 1.2)
>
> even once that's done, you'd still need the patch (or a similar patch) I'm
> suggesting for this infrastructure to work on NVIF-based platforms. userspace
> logic for parsing the NVIF methods would also be needed; I'm working on getting
> sign-off to release that IP for general linux support.

Yeah, this is the bit I don't understand. The design we've adopted for
output switching ignores any BIOS provided information, and instead just
enables outputs based on the user preferences. The X driver then has
responsibility for performing the actual switch. Nouveau appears to be
able to handle this on nvidia platforms without any problem. So, really,
I guess I'm not clear on what functionality NVIF is intended to provide
here. Is it impossible to enable outputs on some systems without it?

--
Matthew Garrett | mjg59@srcf.ucam.org