AGPGART driver for ArticiaS - ioremap() problem

Benjamin Herrenschmidt benh at
Thu Jan 19 10:09:11 EST 2006

On Wed, 2006-01-18 at 20:40 +0100, Gerhard Pircher wrote:
> > > That's the problem: we don't have the datasheet for the ArticiaS. :-( 
> > > But the driver initializes correctly with the Uninorth code now and
> > > with the DRI/DRM code changed. (The code in drm_vm.c checks for Apple's
> > > PCI vendor ID. Therefore I just added a check for MAI's PCI vendor ID.)
> > > But the X server freezes after the login screen is displayed (IIRC the
> > > mouse still works, but the keyboard is dead!?).
> > 
> > That check is only necessary because Apple bridge puts the AGP aperture
> > at bus address 0. This is probably not the case for you. You may not
> > have that right. Check what you put in agp_bridge->gart_bus_addr

> Hmm, I'm not sure what value agp_bridge->gart_bus_addr should have. The BIOS
> doesn't setup it and the VIA AGPGART driver even reads it out from the
> northbridge's registers! Where does the value for agp_bridge->gart_bus_addr
> come from? For now it is set to 0x0, which would require the modification in
> drm_vm.c!?

Well... this is where you AGP aperture will be in bus space.. you'd
rather know what to do with it to do a driver...

> :) The driver seems to work better with cant_use_aperture set to 1, so I
> leave it as it is. BTW: What's the meaning of needs_scratch_page?

Well, set to 1 would mean the aperture isn't accessible on the CPU
space. It might seem to work better either because indeed that is the
case... or simply because you put it in a wrong place (ie 0 !) There
must be a chipset register somewhere that tells you where the aperture
is no ?


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