Re: [patch] radeonfb: FB_WAITFORVSYNC implementation

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Sat, 2005-03-12 at 11:21 -0500, Jon Smirl wrote:
> On Sat, 12 Mar 2005 18:10:40 +0200, Ville Syrjälä <syrjala@sci.fi> wrote:
> > On Sat, Mar 12, 2005 at 11:00:56AM -0500, Jon Smirl wrote:
> > > On Sat, 12 Mar 2005 17:51:39 +0200, Ville Syrjälä <syrjala@sci.fi> wrote:
> > > > It's not a problem if one doesn't use X.Org/XFree86. Also this patch
> > > > should not affect X.Org/XFree86 users unless they manage to call the
> > > > FBIO_WAITFORVSYNC ioctl. matroxfb and atyfb both have similar interrupt
> > > > support and X can still be used with both.
> > >
> > > Almost all PPC Linux boxes are running radeonfb with Xorg.
> > 
> > What's your point? I doubt X.Org uses FBIO_WAITFORSYNC so the patch
> > should not interfere with anything.
> 
> Run something on one VT that uses radeonfb with FBIO_WAITFORSYNC.
> Switch to VT with xorg.
> Reboot box.

Not necessarily. We have the concept of active VT. FBIO_WAITFORSYNC only
need to enable interrupts during the ioctl execution, and mail stop
waiting and return an error if blank/set_var is called (and thus a VT
switch happens).

Ben.




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