linux-kernel - Re: [PATCH 01/16] Blackfin SPI Driver: ensure cache coherency before doing DMA

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Date:	Thu, 5 Feb 2009 17:30:06 +0800
From:	Bryan Wu <cooloney@...nel.org>
To:	David Brownell <david-b@...bell.net>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Mike Frysinger <vapier.adi@...il.com>,
	spi-devel-general@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org,
	Vitja Makarov <vitja.makarov@...il.com>
Subject: Re: [PATCH 01/16] Blackfin SPI Driver: ensure cache coherency before 
	doing DMA

On Fri, Nov 21, 2008 at 6:05 AM, David Brownell <david-b@...bell.net> wrote:
> On Thursday 20 November 2008, Mike Frysinger wrote:
>> On Thu, Nov 20, 2008 at 16:47, David Brownell wrote:
>
>> > Basically, dma_map_single(), dma_unmap_single() ... and
>> > remember that the caller may have done the mappings for
>> > you already.
>>
>> these arent required to provide coherent memory right ?  if that's the
>> case, i can take a look at getting things updated.
>
> Right.  If caller provides dma-coherent memory to you, they
> must also have provided the DMA addresses the controller
> driver should be using ... so you won't need dma mapping
> calls on those paths.
>
>
>> > It'd be nice if one of patches snuck in a comment on that
>> > point:  "Full duplex only works for non-DMA transfers."
>> > Same rationale:  you may know this hardware inside out,
>> > but the next person won't.
>>
>> well, hopefully if they dont know they wont be touching the driver ;).
>>  i'll add a comment in this code chunk.  thanks for the feedback.
>
> The way it usually works is someone observes a problem and
> then starts experimenting on relevant code.  So they learn
> a bit while debugging ... and code authors/maintainers need
> to keep that learning curve from being too steep.  ;)
>
> - Dave
>
>

Hi Dave,

As you acked this patchset, is that possible to merge it?
Or need Andrew to keep them in -mm for a while.

Thanks
-Bryan
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