Re: patch for video.c driver

[Terence Ripperda <tripperda@nvidia.com>]

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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