linux-kernel - Re: [PATCH v2 4/4] media: pxa_camera: conversion to dmaengine

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Date:	Sun, 12 Jul 2015 19:33:09 +0200
From:	Robert Jarzmik <robert.jarzmik@...e.fr>
To:	Guennadi Liakhovetski <g.liakhovetski@....de>
Cc:	Mauro Carvalho Chehab <mchehab@....samsung.com>,
	Jiri Kosina <trivial@...nel.org>, linux-media@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 4/4] media: pxa_camera: conversion to dmaengine

Guennadi Liakhovetski <g.liakhovetski@....de> writes:

>>  		/* init DMA for Y channel */
>
> How about taking the loop over the sg list out of pxa_init_dma_channel() 
> to avoid having to iterate it from the beginning each time? Then you would 
> be able to split it into channels inside that global loop? Would that 
> work? Of course you might need to rearrange functions to avoid too deep 
> code nesting.

Ok, will try that.
The more I think of it, the more it looks to me like a generic thing : take an
sglist, and an array of sizes, and split the sglist into several sglists, each
of the defined size in the array.

Or more code-like speaking :
  - sglist_split(struct scatterlist *sg_int, size_t *sizes, int nb_sizes,
                 struct scatterlist **sg_out)
  - and sg_out is an array of nb_sizes (struct scatterlist *sg)

So I will try that out. Maybe if that works out for pxa_camera, Jens or Russell
would accept that into lib/scatterlist.c.

Cheers.

--
Robert
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