Subject: Re: [PATCH] dmaengine: Add API documentation for slave dma usage
From: "Koul, Vinod" <vinod.koul@intel.com>
To: Per Forlin <per.forlin@linaro.org>
Cc: Dan Williams <dan.j.williams@intel.com>,
        Linus Walleij <linus.walleij@linaro.org>,
        Russell King <linux@arm.linux.org.uk>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-arm-kernel@lists.infradead.org
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Date: Wed, 25 May 2011 15:04:42 +0530
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On Wed, 2011-05-25 at 11:47 +0200, Per Forlin wrote:
> On 25 May 2011 10:26, Koul, Vinod <vinod.koul@intel.com> wrote:
> > I am okay with making this same for the slave devices as well.
> >
> > That would also require to change few drivers which start the txn in
> > submit()
> Yes,
> The trivial part is to move enable from submit to issue_pending. I had
> a quick look and it looks like the following drivers need to be
> changed.
> mpc512x_dma.c
> imx-dma.c
> imx-sdma.c
> mxs-dma.c
> 
> The other part is more complex. To make submit only add descs to a
> queue that will be pushed down to the DMA only after issue_pending. It
> is not as trivial to identify which of the drivers support this or
> not.
> I still think it make sense to fix the documentation first and then
> fix the drivers. Keep a list inside the dmaengine.txt of drivers that
> need to be fixed in order to comply with the API. Over time drivers
> will be fixed and removed from the list. When we have agreed upon the
> API (we may not be there yet) I am willingly to make a draft of such a
> list.
Yes this sounds right, I will send updated version and now drivers would
need to call issue_pending.

I know dw_dmac, intel_mid_dma and ste_dma40 would need changes as well.

Was thinking to add TODO in drivers/dma with these and any other changes
we feel are required moving forward.
We need dw_dmac to be moved to new slave interface and remove old slave
pointer mechanism when all are moved. 

-- 
~Vinod

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