Re: [PATCH] Fix switch from XFree

[Sven Luther <sven.luther@wanadoo.fr>]

On Tue, Feb 10, 2004 at 09:36:42PM +1100, Benjamin Herrenschmidt wrote:
> Hi James !
> 
> (This patch includes the one adding the lock around the notifier
> registration so you can drop that previous one)
> 
> Currently, there is a problem when switching from XFree to a console
> that became especially annoying now that we have some accelerations
> in radeonfb 2.6. XFree leaves the accel engine in a state that is
> incorrect for our accel operations. This problem is generic with most
> drivers, we can't expect X to leave the accel engine in the right
> state, that's simply unrealistic.

Mmm, i wonder about this. The X driver is supposed to be responsible for
saving and reseting the engine when leaving/entering. This is usually
done in a separate way when using or not using fbdev.

Now, if we are going to save/restore the contect too, then this would
mean a risk of dual saving the engine state. Or maybe the X server
doesn't really save the context, but just reinitialize it when entering.

I have the feeling that more working together would be helpfull, or
maybe setup a proper policy for X/fbdev to handle this properly.

Maybe the fbdev driver could set a flag or something, which would tell
the X server that it is taking charge of saving/restoring the accel
engine, so the X driver would not try doing this too, at least in the
UseFBDev case (but do we care about the other case ?).

Friendly,

Sven Luther


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