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From: Wolfram Sang <wsa@the-dreams.de>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linux I2C <linux-i2c@vger.kernel.org>,
	Linux-sh list <linux-sh@vger.kernel.org>,
	Magnus Damm <magnus.damm@gmail.com>,
	Simon Horman <horms@verge.net.au>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Subject: Re: [RFC 0/2] i2c: sh_mobile: don't regress on deferred probing
Date: Wed, 10 Dec 2014 15:19:12 +0100	[thread overview]
Message-ID: <20141210141912.GA8247@katana> (raw)
In-Reply-To: <CAMuHMdUwsUakz7S_7xCob4__wR-PXcdpZKTGx0i_6ZatDeSvXg@mail.gmail.com>

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> On Wed, Dec 10, 2014 at 2:21 PM, Wolfram Sang <wsa@the-dreams.de> wrote:
> > Okay, here is my take on solving the problem found by Geert. I still don't like
> > it much but it is not as bad as I expected it to be ;) Let me know what you
> > think.
> 
> Thanks, it's indeed less ugly than I would have expected ;-)

:D

> Note that in spi-rspi.c and spi-sh-msiof, any error returned by *_request_dma()
> is considered an error, and -EPROBE_DEFER is not handled specially.
> So it won't retry if the DMA engine driver isn't available, but just use PIO
> (until unbind/bind).

For historic reasons, i2c-sh_mobile uses subsys_initcall() and at that
time, DMA is never available. Converting to module_init() will just
create its own set of potential regressions :(

> Now we have a nice sample implementation, perhaps I should port it to
> spi-rspi and spi-sh-msiof, too?
> 
> Let's wait and see for other comments...

Yeah, let's see first...


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      reply	other threads:[~2014-12-10 14:19 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-12-10 13:21 [RFC 0/2] i2c: sh_mobile: don't regress on deferred probing Wolfram Sang
2014-12-10 13:21 ` [RFC 2/2] i2c: sh_mobile: rework " Wolfram Sang
2014-12-10 13:44   ` Geert Uytterhoeven
2014-12-16 11:35     ` Wolfram Sang
     [not found] ` <1418217709-26392-1-git-send-email-wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>
2014-12-10 13:21   ` [RFC 1/2] i2c: sh_mobile: refactor DMA setup Wolfram Sang
2014-12-10 19:06     ` Sergei Shtylyov
2014-12-16 11:34       ` Wolfram Sang
2014-12-16 21:06         ` Sergei Shtylyov
2014-12-10 13:49   ` [RFC 0/2] i2c: sh_mobile: don't regress on deferred probing Geert Uytterhoeven
2014-12-10 14:19     ` Wolfram Sang [this message]

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