Re: [PATCH V2 1/4] arm: mvebu: increase atomic coherent pool sizefor armada 370/XP

[Sebastian Hesselbarth]

On 11/06/2012 11:32 PM, Andrew Lunn wrote:
> On Tue, Nov 06, 2012 at 10:28:45PM +0100, S?ren Moch wrote:
> > I see a regression from linux-3.5 to linux-3.6 and think there might
> > be a fundamental problem
> > with this patch. On my Kirkwood system (guruplug server plus) with
> > linux-3.6.2 I see following
> > errors and corresponding malfunction even with further increased
> > (2M, 4M) pool size:
> >
> > Oct 19 00:41:22 guru kernel: ERROR: 4096 KiB atomic DMA coherent
> > pool is too small!
> > Oct 19 00:41:22 guru kernel: Please increase it with coherent_pool=
> > kernel parameter!
> >
> > So I had to downgrade to linux-3.5 which is running without problems.
> >
> > I use SATA and several DVB sticks (em28xx / drxk and dib0700).
>
> I'm guess its the DVB sticks which are causing the problems. We have a
> number of kirkwood devices with two SATA devices which had problems
> until we extended the coherent_pool. The DVB sticks are probably take
> more coherent RAM. There was also an issue found recently:
>
> http://www.spinics.net/lists/arm-kernel/msg203962.html
>
> That conversation has gone quiet, but that could be because the
> participants are at ELCE.

So what is the call here? Should we just increase the coherent buffer
size back to what it was before? I am not into this too much but just
increasing the buffer will just postpone the actual issue to a later
point in running the kernel?

Sebastian
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