linux-kernel - Re: [PATCH 1/3] ata: sata_dwc_460ex: use "dmas" DT property to find dma channel

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Message-ID: <yw1xmvsgz6c7.fsf@unicorn.mansr.com>
Date:	Fri, 08 Jan 2016 10:57:44 +0000
From:	Måns Rullgård <mans@...sr.com>
To:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:	Andy Shevchenko <andy.shevchenko@...il.com>,
	Julian Margetson <runaway@...dw.ms>, Tejun Heo <tj@...nel.org>,
	linux-ide@...r.kernel.org,
	"linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] ata: sata_dwc_460ex: use "dmas" DT property to find dma channel

Andy Shevchenko <andriy.shevchenko@...ux.intel.com> writes:

> On Thu, 2016-01-07 at 18:32 +0000, Måns Rullgård wrote:
>
>> Andy Shevchenko <andriy.shevchenko@...ux.intel.com> writes:
>> 
>> > On Wed, 2016-01-06 at 19:36 +0200, Andy Shevchenko wrote:
>> > > 
>> > So, Måns, Julian, I just have published my repository containing
>> > Måns' and my patches regarding dw_dmac and sata_dwc_460ex drivers
>> > here
>> > 
>> > https://bitbucket.org/andy-shev/linux/branch/topic%2Fdw%2Fnext
>> 
>> I've picked out the relevant changes from your branch and made some
>> additional improvements.  A few notes:
>> 
>> - The __be32/__le32 typedefs for the DMA descriptor fields are necessary
>>   to avoid a million sparse warnings (and sparse is correct to warn).
>
> Hmm… Which version of sparse are you using? I always run builds with
> sparse enabled and didn't see anything.

You need to enable endian checking with CF=-D__CHECK_ENDIAN__

>> - Using #ifdef CONFIG_AVR32 is a step back, IMO, since this driver may
>>   well be used on another big endian system some day.  The Kconfig logic
>>   for selecting this option could perhaps be improved though.
>
> Maybe runtime chosen accessors will be better than ifdefs?

Are there any systems that could otherwise run the same kernel that use
this hardware with different byte order?  I doubt it.

> I don't like the Kconfig option which limits application of the
> (compiled) driver.

It's no more limited than a hard #ifdef AVR32 in the driver code.

-- 
Måns Rullgård