Re: [RFC PATCH 08/13] mmc: omap_hsmmc: limit max_segs with the EDMADMAC

[Felipe Balbi]

On Fri, Sep 21, 2012 at 10:47:30PM +0530, S, Venkatraman wrote:
> On Fri, Sep 21, 2012 at 10:45 PM, S, Venkatraman <svenkatr@xxxxxx> wrote:
> > On Thu, Sep 20, 2012 at 8:13 PM, Matt Porter <mporter@xxxxxx> wrote:
> >> The EDMA DMAC has a hardware limitation that prevents supporting
> >> scatter gather lists with any number of segments. Since the EDMA
> >> DMA Engine driver sets the maximum segments to 16, we do the
> >> same.
> >>
> >> Note: this can be removed once the DMA Engine API supports an
> >> API to query the DMAC's segment limitations.
> >>
> >
> > I wouldn't want to bind the properties of EDMA to omap_hsmmc as this patch
> > suggests. Why don't we have a max_segs property, which when explicitly specified
> > in DT, will override the default ?
> 
> If you are adventurous, this can be a generic mmc DT binding instead
> of restricting it to OMAP.

I say if it's a limitation in the DMAC, then DMAC's driver should handle
it, no ? Meaning that in this case you would copy from one multi-segment
sg into a one-segment sg and when transfer is complete, before calling
user's callback, copy data the other way around (?)

-- 
balbi

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