Re: [PATCH v2 05/11] ASoC: fsl-ssi: Add support for imx-pcm-fiq

[Markus Pargmann <mpa-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>]

On Sun, Apr 14, 2013 at 09:53:57AM -0500, Timur Tabi wrote:
> Markus Pargmann wrote:
> >In general, imx27 does support SSI with DMA, for example
> >MACH_IMX27_VISSTRIM_M10 does use SSI with DMA. But there are special
> >boards like Eukrea TLV320 and phycore-ac97 that have to use FIQ instead.
> >All of them have a imx27 chip.
> 
> Why is the decision to use FIQ board-specific?  All of the hardware
> is inside the SoC itself.  How could a board make using DMA
> impossible?

I only ported the imx-ssi ac97 driver code and tested twice using DMA
without success. But there is a good description of the problem in
imx-ssi:

" The WM9712 with which this driver
was developed with always sends GPIO status data in slot 12 which
we receive in our (PCM-) data stream. The only chance we have is to
manually skip this data in the FIQ handler."

Regards,

Markus

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