Re: [PATCH 00/33] devm improvement series, part 1, take 2

From: Thierry Reding <thierry.reding@avionic-design.de>
To: Wolfram Sang <wsa@the-dreams.de>
Cc: linux-mips@linux-mips.org, alsa-devel@alsa-project.org,
	linux-usb@vger.kernel.org, Liam Girdwood <lgirdwood@gmail.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Linus Walleij <linus.walleij@linaro.org>,
	Matt Mackall <mpm@selenic.com>,
	linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org,
	Jaroslav Kysela <perex@perex.cz>,
	linux-ide@vger.kernel.org, netdev@vger.kernel.org,
	linux-mtd@lists.infradead.org, linux-i2c@vger.kernel.org,
	Evgeniy Polyakov <zbr@ioremap.net>,
	Wan ZongShun <mcuos.com@gmail.com>,
	ac100@lists.launchpad.net, devel@driverdev.osuosl.org,
	Kukjin Kim <kgene.kim@samsung.com>,
	Russell King <linux@arm.linux.org.uk>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	Florian Tobias Schandinat <FlorianSchandinat@gmx.de>,
	Stephen Warren <swarren@wwwdotorg.org>,
	"Rafael J. Wysocki" <rjw@sisk.pl>,
	cpufreq@vger
Subject: Re: [PATCH 00/33] devm improvement series, part 1, take 2
Date: Thu, 23 May 2013 22:32:43 +0200	[thread overview]
Message-ID: <20130523203243.GA18069@avionic-0098.adnet.avionic-design.de> (raw)
In-Reply-To: <1368702961-4325-1-git-send-email-wsa@the-dreams.de>

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On Thu, May 16, 2013 at 01:15:28PM +0200, Wolfram Sang wrote:
> Lately, I have been experimenting how to improve the devm interface to make
> writing device drivers easier and less error prone while also getting rid of
> its subtle issues. I think it has more potential but still needs work and
> definately conistency, especiall in its usage.
> 
> The first thing I come up with is a low hanging fruit regarding
> devm_ioremap_resouce(). This function already checks if the passed resource is
> valid and gives an error message if not. So, we can remove similar checks from
> the drivers and get rid of a bit of code and a number of inconsistent error
> strings.

Sorry for jumping in so late. I generally like the idea. One small
inconvenience is that devm_ioremap_resource() returns -EINVAL if
res == NULL, which means that drivers will now also return -EINVAL
in cases where no resource was returned. Typically drivers handle
this by returning something like -ENODEV, -ENXIO, -ENOENT. Some do
return -EINVAL but perhaps having a separate error code (and maybe
error message as well) for a missing resource would be helpful.

Doing this would be rather easy now that you've paved the way by
making devm_ioremap_resource() usage consistent across drivers.

Thierry

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