Re: [Linux-fbdev-devel] [PATCH] Tile Blitting

[James S. <jsi...@in...>]

> On Don, 2003-02-27 at 15:15, Antonino Daplas wrote: 
> > On Thu, 2003-02-27 at 09:18, James Simmons wrote:
> >  
> > > > Thus, the restriction that the buffer must be completely copied by the
> > > > driver before returning.  And because of this restriction, an extra copy
> > > > which might be unnecessary cannot be avoided (this was noted by Petr).
> > > > 
> > > > Treating the buffer as a ringbuffer, we eliminate these restrictions.
> > > 
> > > I didn't realize that the below was a ringbuffer implementation. The name
> > > threw me off. 
> > 
> > Well, it's not strictly a ringbuffer implementation.  This would require
> > a head and tail pointer where fbcon will adjust the tail and the
> > driver/hardware will adjust the head.  This will be very difficult to
> > implement in a device independent manner.  So we just cheat by issuing
> > an fb_sync() per loop to flush all pending commands.
> 
> That still seems suboptimal though. What the DRM often does is have the
> chip write an age value to a scratch register when it's done processing
> something. Maybe something like that could be used to avoid waiting for
> the chip to go idle at all?

Don't waste your time. I'm removing all the changes that have been done 
since 2.5.51. After that I will no longer be co-maintainter of the 
framebuffer layer.