Date: Wed, 30 Sep 2009 15:55:57 +0200
From: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
To: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, linux-mmc@vger.kernel.org,
       linux-kernel@vger.kernel.org, kernel@avr32linux.org,
       Hans-Christian Egtvedt <hcegtvedt@atmel.com>
Subject: Re: [PATCH 1/2] atmel-mci: change use of dma slave interface
Message-ID: <20090930155557.7dae503b@hskinnemoen-d830>
In-Reply-To: <4AC35E1D.7040802@atmel.com>
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Nicolas Ferre <nicolas.ferre@atmel.com> wrote:
> > You'll still need typecasts to support the dma_request_channel()
> > callback, but the code will be safer and cleaner, I expect.  
> 
> My concern are:
> 1/ allow the use of either dmaengine driver
> 2/ avoid too much modification to dw_dma_slave as it
> is also used for audio stuff on avr32 platforms...
> 3/ not introduce heavy weigh solution like the use of an union

We used to have a struct dma_slave in linux/dmaengine.h which took care
of all this, but it got removed at some point.

How about introducing a new mach/atmel-mci.h file with a struct
mci_dma_data encapsulating either a struct dw_dma_slave or a struct
at_dma_slave, as well as any other DMA-related definitions needed by
the atmel-mci driver?

Then we just need to make sure that we either
  1) use the same name on all fields in struct {dw,at}_dma_slave which
     are used by the atmel-mci driver, or
  2) add accessor functions or macros for those fields.

I think I would prefer the latter, but both should work equally well.

Haavard
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