Re: [PATCH 07/15] dmaengine: dw: revisit data_width property

[Andy Shevchenko <andriy.shevchenko-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>]

On Mon, 2016-01-25 at 10:31 +0000, Måns Rullgård wrote:
> Andy Shevchenko <andriy.shevchenko-VuQAYsv1563Yd54FQh9/CA@public.gmane.org> writes:
> 
> > On Mon, 2016-01-25 at 07:32 +0000, Vineet Gupta wrote:
> > > On Monday 25 January 2016 12:55 AM, Mans Rullgard wrote:

> > > > --- a/Documentation/devicetree/bindings/dma/snps-dma.txt
> > > > +++ b/Documentation/devicetree/bindings/dma/snps-dma.txt
> > > > @@ -13,8 +13,7 @@ Required properties:
> > > >  - chan_priority: priority of channels. 0 (default): increase
> > > > from
> > > > chan 0->n, 1:
> > > >    increase from chan n->0
> > > >  - block_size: Maximum block size supported by the controller
> > > > -- data_width: Maximum data width supported by hardware per AHB
> > > > master
> > > > -  (0 - 8bits, 1 - 16bits, ..., 5 - 256bits)
> > > > +- data-width: Maximum data width supported by hardware (in
> > > > bytes)
> > > 
> > > To the reader this suggests a value truely byte granular, but
> > > code
> > > uses ffs
> > > implying that it is still power of 2.
> > > Can you mention this here (....in bytes, always power of 2).
> > 
> > While this comment is good, I have still note that using non-power
> > of 2
> > values will not break anything. Least power of two number will be
> > used
> > in that case. So, means I would suggest to replace 'always' by
> > 'better
> > to be' or something like that.
> 
> Although the code rounds down, the hardware actually works in powers
> of
> two, and it's better to document this.

Let's do "(in bytes, power of 2)" then?

-- 
Andy Shevchenko <andriy.shevchenko-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
Intel Finland Oy

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