Re: [patch] radeonfb: FB_WAITFORVSYNC implementation

[Torgeir Veimo <torgeir@pobox.com>]

On Sun, 2005-03-13 at 10:30 +1100, Benjamin Herrenschmidt wrote:
> On Sat, 2005-03-12 at 14:06 +0000, Torgeir Veimo wrote:
> > This is an implementation of the FB_WAITFORVSYNC ioctl for the radeonfb.
> > A small test application is attached at the end. This patch is against
> > vanilla 2.6.11. 

> The patch definitely needs a lot of cleanups. A few things are wrong
> too, like using test_and_set_* as a mean of locking. This doesn't work
> on relaxed ordering architectures.
> 
> Besides, the entire fbdev subsystem is protected by the console
> semaphore, so you shouldn't need anything else. You need to acquire it
> yourself in the driver ioctl() routine though.
> 
> In order to avoid conflicting with other apps, you should probably
> "abort" the operation if a console switch happens while you are waiting.
> That is, a set_var() and/or a blank(). Return -EINTR or something like
> that.

Do you have any example code I can look at for this? From what I can see
neither the atyfb or matroxfb drivers do this. Not that I'm claiming
they're correct, I guess the current vanilla kernel source is a bit
behind the latest and greatest fb development. 

-- 
Torgeir Veimo <torgeir@pobox.com>



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