Re: patch for video.c driver

Terence Ripperda
2009-03-13T20:45:47Z

On Fri, Mar 13, 2009 at 11:06:46AM -0700, mjg59@srcf.ucam.org wrote:
> On Fri, Mar 13, 2009 at 12:58:12PM -0500, Terence Ripperda wrote:
> > On Fri, Mar 13, 2009 at 10:47:26AM -0700, mjg59@srcf.ucam.org wrote:
> > > 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?
> >
> > yes, this is what I mean by platform customizations. some notebook platforms
> > will rely on the DCS/DGS methods to perform hotkeys, others will rely on other
> > mechanisms, such as NVIF methods. I suspect you'll find that nouveau's mechanism
> > will work on a lot of notebooks, but not work at all on other notebooks.
>
> Can we make sure we're clear on terminology here? I'm using hotkey
> events to refer purely to the process by which the user hits a key, the
> firmware generates a notification, the kernel catches this notification
> and generates a KEY_SWITCHVIDEOMODE which we then catch in the user
> session.
>
> There's then the issue of actually performing a display output change in
> response to this. This is curently handled by generating an xrandr
> request. The X driver (potentially in combination with the kernel
> driver, in a kernel modesetting world) then enables or disables outputs
> as appropriate.
>
> The actual output changing is related to but not dependent upon the
> hotkey press, as the user may want to change output configuration via
> the graphical UI rather than by hitting the hotkey. So is the NVIF
> functionality required for generating the event in the first place,
> performing the actual output switch or simply providing the firmware's
> preferred set of enabled outputs?

sure, I sometimes use the wrong terminology; I mean a display change hotkey,
where a keypress generates a display change event via the sbios/acpi subsystem.

I do not mean a case where a userspace daemon detects keypresses independent of
the sbios/acpi/kernel. I was trying to clarify whether nouveau was using such a
mechanism.

NVIF methods implement both notification and query commands. so it's required
for generating the event and querying the firmware's preferred set of enabled
outputs.

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

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