RandR bugs

Thomas Winischhofer thomas at winischhofer.net
Thu Sep 29 17:43:14 PDT 2005

Hash: SHA1

Andy Ritger wrote:
> On Fri, 30 Sep 2005, Thomas Winischhofer wrote:
> There is one little issue, namely identically looking metamodes (ie meta
> modes that consist of different modes for the output devices, but look
> the same to the server, eg 1280x1024-1024x768 and 1024x768-1280x1024). I
> work around the problem that RandR ignores the second one of these modes
> (because it thinks that they are identical) by giving the second one a
> different rate.
>> :)  We had come up with the same solution in the NVIDIA driver,
>> and I was feeling dirty about it.  Now I don't feel so bad.

Well, it works and I have done this a while ago.. the feeling fades :)

> Andy, does the Nvidia driver support rotation in TwinView mode? I have
> been thinking about this, but it's logically somewhat beyond me yet,
> especially when it comes to non-rectangular screens.
>> Yeah, this is somewhat problematic.  Today, it sort of works by
>> accident, depending on what you want to do.  People who want two
>> rotated displays positioned horizontally can configure something
>> like this:
>>     1280x1024+0+0, 1280x1024+0+1024
>> to position the unrotated displays vertically, and then rotate the
>> whole X screen.

But that means it isn't switchable run-time, is it?

>> Having per-display device control of rotation is something that
>> I don't think RandR can currently do.  

(Only in true dual head mode)

>> I've been leaning towards
>> handling the rotation control within the driver, and just exporting
>> MetaModes out to RandR that are the bounding box; eg:
>>     1280x1024, 1024x1280
>> (and yes, you'd end up with a dead region... could use a panning
>> domain "1280x1024 at 1280x1280, 1024x1280" such that you can pan the
>> first display to access that region of the screen, but ick)
>> RandR would unfortunately no longer know about the rotation, though.
>> We've not actually implemented that, yet, though.

What you describe all together were my thoughts of the last few days.
Haven't come up with a really smart solution yet either. Nice to see
that even NVidia can't work mircacles :)


- --
Thomas Winischhofer
thomas AT winischhofer DOT net          http://www.winischhofer.net/

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