Re: [PATCH] [RFC] Xilinx MPMC SDMA subsystem

[Grant Likely <grant.likely@secretlab.ca>]

On Mon, Mar 29, 2010 at 9:42 AM, Steven J. Magnani
<steve@digidescorp.com> wrote:
> On Fri, 2010-03-26 at 17:53 -0600, Grant Likely wrote:
>> I've not got time to review this patch right now, but Sergey and
>> Steven, you both posted MPMC drivers on the same day; Steven on the
>> microblaze list and Sergey on the powerpc list. =A0Can you two please
>> coordinate and figure out how to mork toward a single driver that will
>> meet both your needs? =A0I don't want to have 2 drivers (3 if you count
>> the ll_temac driver) in mainline for the same hardware interface.
>>
>
> I don't think we'll end up with a single driver. A MPMC DMA Engine
> driver is useful only on "loopback" SDMA ports. Sergey's code looks like
> a nice generic interface to Xilinx SDMA HW that could be used by the
> xlldma and ll_temac drivers, for instance. Both of those will get
> smaller, but won't go away.
>
> For this to be useful to me, it would need to be located somewhere more
> accessible than arch/powerpc and it would need to have initialization
> methods that don't depend on OF. In my build I would have platform code
> that binds to the xlldma platform attachment, which would call Sergey's
> SDMA code to assign it the proper resources.

That should be fine.

> Any objections to having Sergey's code live in drivers/dma, and putting
> sdma.h out in include/linux? Might need to tweak the file/function names
> some to head off namespace issues. Or is there some other strategy for
> managing Xilinx-related drivers common to both Microblaze and PowerPC?

I have no objections.  This sounds like a good plan.

g.

--=20
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.