Re: [PATCH] ata: sata_mv: fix sg_tbl_pool alignment

[Jason Cooper <jason@lakedaemon.net>]

On Wed, Jan 16, 2013 at 06:05:59PM +0100, Soeren Moch wrote:
> On 16.01.2013 16:50, Jason Cooper wrote:
> >On Wed, Jan 16, 2013 at 09:55:55AM +0100, Soeren Moch wrote:
> >>On 16.01.2013 04:24, Soeren Moch wrote:
> >>>On 16.01.2013 03:40, Jason Cooper wrote:
> >>>>On Wed, Jan 16, 2013 at 01:17:59AM +0100, Soeren Moch wrote:
> >>>>>On 15.01.2013 22:56, Jason Cooper wrote:
> >>>>>>On Tue, Jan 15, 2013 at 03:16:17PM -0500, Jason Cooper wrote:
> >
> >>OK, I could trigger the error
> >>   ERROR: 1024 KiB atomic DMA coherent pool is too small!
> >>   Please increase it with coherent_pool= kernel parameter!
> >>only with em28xx sticks and sata, dib0700 sticks removed.
> >
> >Did you test the reverse scenario?  ie dib0700 with sata_mv and no
> >em28xx.
> 
> Maybe I can test this next night.

Please do, this will tell us if it is in the USB drivers or lower
(something in common).

> >>>>What would be most helpful is if you could do a git bisect between
> >>>>v3.5.x (working) and the oldest version where you know it started
> >>>>failing (v3.7.1 or earlier if you know it).
> >>>>
> >>>I did not bisect it, but Marek mentioned earlier that commit
> >>>e9da6e9905e639b0f842a244bc770b48ad0523e9 in Linux v3.6-rc1 introduced
> >>>new code for dma allocations. This is probably the root cause for the
> >>>new (mis-)behavior (due to my tests 3.6.0 is not working anymore).
> >>
> >>I don't want to say that Mareks patch is wrong, probably it triggers a
> >>bug somewhere else! (in em28xx?)
> >
> >Of the four drivers you listed, none are using dma.  sata_mv is the only
> >one.
> 
> usb_core is doing the actual DMA for the usb bridge drivers, I think.

Yes, my mistake.  I'd like to attribute that statement to pre-coffee
rambling. :-)

> >If one is to believe the comments in sata_mv.c:~151, then the alignment
> >is wrong for the sg_tbl_pool.
> >
> >Could you please try the following patch?
> 
> OK, what should I test first, the setup from last night (em28xx, no
> dib0700) plus your patch, or the reverse setup (dib0700, no em28xx)
> without your patch, or my normal setting (all dvb sticks) plus your
> patch?

if testing time is limited, please do the test I outlined at the top of
this email.  I've been digging more into the dma code and while I think
the patch is correct, I don't see where it would fix your problem (yet).

thx,

Jason.