On Fri, May 16, 2014 at 01:55:01PM +0100, Catalin Marinas wrote:
> On Thu, May 15, 2014 at 05:53:53PM +0100, Liviu Dudau wrote:
> > On Thu, May 15, 2014 at 04:36:25PM +0100, Alan Stern wrote:
> > > On Thu, 15 May 2014, Liviu Dudau wrote:
> > > > On Thu, May 15, 2014 at 03:11:48PM +0100, Alan Stern wrote:
> > > > > On Wed, 14 May 2014, Mark Brown wrote:
> > > > > > arm64 architecture handles correctly 64bit DMAs and can enable
> > > > > > support
> > > > > > for 64bit EHCI host controllers.
> > > > >
> > > > > Did you folks tested this for all sorts of host controllers? I have
> > > > > no
> > > > > way to verify that it works, and last I heard, many (or even most)
> > > > > controllers don't work right with 64-bit DMA.
> > > >
> > > > I have tested it with a host controller that is capable of 64-bit DMA
> > > > and
> > > > without this change it doesn't work.
> > >
> > > What do you mean it doesn't work? Can't the host controller use 32-bit
> > > DMA?
> >
> > It could if arm64 would restrict the DMA addresses to 32-bit, but it doesn't
> > and I end up on my platform with USB DMA buffers allocated >4GB address.
>
> dma_alloc_coherent() on arm64 should return 32-bit addresses if the
> coherent_dma_mask is set to 32-bit. Which kernel version is this?
The initial patch was created before the removal of DMA32_ZONE from arm64. I
need
to revisit the latest mainline kernel on my board to determine if this patch is
still needed.
Best regards,
Liviu
>
> --
> Catalin
--
====================
| I would like to |
| fix the world, |
| but they're not |
| giving me the |
\ source code! /
---------------
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