Subject: Re: PowerPC radeon KMS - is it possible?

From: Michel Dänzer <[email-masked]>
Date: Wed, 18 Apr 2012 18:06:36 +0200

On Mit, 2012-04-18 at 17:49 +0200, Gerhard Pircher wrote: 
> > Von: "Michel Dänzer" <[email-masked]>
> > On Mit, 2012-04-18 at 16:55 +0200, Andreas Schwab wrote: 
> > > Michel Dänzer <[email-masked]> writes:
> > > 
> > > > On Mit, 2012-04-18 at 16:28 +0200, Andreas Schwab wrote: 
> > > >> Michel Dänzer <[email-masked]> writes:
> > > >> 
> > > >> > Have you tried smaller aperture sizes (uninorth_agp.aperture)
> > > >> > and/or radeon.test=1? (See commit
> > > >> > 52f072cb084bbb460d3a4ae09f0b6efc3e7e8a8c)
> > > >> 
> > > >> Neither changes anything.
> > > >
> > > > How small aperture sizes have you tried?
> > > 
> > > 32M. With the old UMS driver 3D once worked fine ...
> > 
> > That doesn't necessarily mean much per se, as with UMS memory is only
> > statically mapped into the AGP GART once (so most of those 32M are
> > wasted at least most of the time), whereas with KMS it's dynamically
> > (un)mapped on demand.
> That may be a stupid question, but is it allowed (for a DRM client or
> whatever does the mapping) to change the content of a page mapped into
> the AGP GART or is it necessary to explicitly unmap the page, change its
> content and map it again?

The former.

> I would say it's necessary to unmap the page first (sounds more like
> the pci_[un]map_page() approach) - at least when it should work with
> non-coherent architectures, too.

I'm afraid non-coherent platforms haven't really been a concern yet for
KMS, and always doing the above dance would probably have a significant
performance impact on coherent platforms.

-- 
Earthling Michel Dänzer           |                   http://www.amd.com
Libre software enthusiast         |          Debian, X and DRI developer