Re: [PATCH 00/13] pxa3xx patches to support mvebu builds

Thomas Petazzoni
2013-07-30T08:18:35Z

Dear Daniel Mack,

On Tue, 30 Jul 2013 10:02:04 +0200, Daniel Mack wrote:
> On 30.07.2013 09:53, Thomas Petazzoni wrote:
> > On Tue, 30 Jul 2013 09:43:54 +0200, Daniel Mack wrote:
> >> Interesting, because I'm working on a dmaengine implementation for
> >> PXA right now. I'm not even half through, but I'm making progress,
> >> and I'm not sure yet how to merge it. Because there won't be any
> >> migration path, it'll be a bigger set that has to go in in one in
> >> order to prevent build breakage.
> >
> > Aren't drivers/dma/mmp_pdma.c and drivers/dma/mmp_tdma.c already
> > dmaengine drivers for PXA ?
>
> Yes, I saw the pdma driver as well, after I started my own
> implementation. However, the tree is full of users of the proprietary
> API, and moving them over won't be gap-less.

Indeed. Some patches migrating the pxa3xx_nand driver to use the
dmaengine API have been posted a while ago, but they haven't been
merged because one needs to convert *all* the PXA drivers to the
dmaengine API to get the thing working.

At Linaro Connect earlier this month, I've talked about this with Chao
Xie from Marvell, and he was interested in making progress towards
dmaengine usage on PXA platforms.

> > Considering the amount of time it will take for PXA to migrate over
> > to the dmaengine API, I think we'd want those clean up patches to
> > go in first, so that in parallel to the work you're doing on PXA
> > dmaengine usage, we can move forward with improving the pxa3xx_nand
> > driver to make it usable on Armada 370/XP.
>
> Ok, fine. I'll rework my set on top of Ezequiel's then.

Excellent, thanks!

Best regards,

Thomas
--
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.