Subject: Re: qtopia
To: Garrett D'Amore <>
From: Michael Lorenz <>
List: tech-kern
Date: 06/03/2006 14:51:06
Hash: SHA1


> I've been intending to add some WSDISPLAY ioctls for managing
> resolutions/modes.  The problem is a little stickier than you might
> suppose at first, especially when you consider devices with multiple
> output ports, etc.

Oh, I'm aware of the stickiness, that's why there is no such API so far.

> Even with a single output port (typically VGA) you
> have the questions of detecting monitor resolutions, virtual vs.
> physical resolutions (you can use a much bigger virtual desktop with
> panning), and e.g. autoexpansion to drive a lower resolution on a 
> higher
> resolution monitor (ratiometric expansion that is supported on Radeon
> and perhaps other devices.)

And then there are things like the FFB which support multiple colour 
depths on the same screen.

> One thing missing is the ability to enable/disable active ports.  (I.e.
> save power by turning off VGA port on a laptop while using the internal
> screen.)

Yeah, the sparcbook has two ports which show the same thing but can be 
powered up and down independently.

> It might also be nice to have an event call back so that applications
> can detect monitor changes.  E.g. some boards have a way to check for
> the existence of a monitor.  (And DVI/TMDS actually has pins defined 
> for
> the purpose.)  But maybe we can leave this a poll interface for now.

Yes, tctrl actually does that and enables the VGA port when it detects 
a monitor.

> No doubt I've missed things.  I've not tried to implement any of this 
> --
> this is all just intended to act as food for thought.  Let me know your
> opinions.

I think video mode and colour depth should be programmed independently, 
especially with boards that support multiple depths simultaneously.

have fun
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