Re: [PATCH 15/15] ARM: mark footbridge as deprecated

["Russell King (Oracle)" <linux@armlinux.org.uk>]

On Wed, Dec 04, 2024 at 04:14:07PM +0100, Linus Walleij wrote:
> On Wed, Dec 4, 2024 at 3:37 PM Russell King (Oracle)
> <linux@armlinux.org.uk> wrote:
> 
> > > I am booting it occasionally, last time to test my KCFI patches.
> > > But admittedly that is only to test it for other SA110 users. I remember
> > > that Christoph had problems consolidating the DMA used in this
> > > machine as well so it is standing in the way of useful work.
> >
> > What problems with DMA? The fact that it uses an offset between
> > physical and PCI bus space should be nothing that causes a problem
> > for the kernel. As maintainer for Footbridge, I've heard nothing
> > about there being any issue.
> 
> No issue other than testing and iterating the patches I think.
> 
> I was thinking of this patchset to do dma_direct_set_offset():
> https://lore.kernel.org/linux-arm-kernel/20200917173229.3311382-3-hch@lst.de/
> 
> It seems to have stalled some years ago, but maybe there was
> some other reason.
> 
> IIRC Christoph was onto me to test it on the NetWinder, but I
> couldn't locate a good DMA capable device to test it with.
> (Would be the soundblaster but then I needed some userspace...)

It isn't soundblaster, but waveartist, and needs special setup to be
functional (which was all in my OSS waveartist driver.)

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