From: Arnd Bergmann <arnd@arndb.de>
To: Stephen Warren <swarren@nvidia.com>
Cc: Jonathan Cameron <jic23@cam.ac.uk>,
Andrew Chew <AChew@nvidia.com>,
"Greg Kroah-Hartman" <gregkh@suse.de>,
Russell King <linux@arm.linux.org.uk>,
"linux-iio@vger.kernel.org" <linux-iio@vger.kernel.org>,
"devel@driverdev.osuosl.org" <devel@driverdev.osuosl.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-tegra@vger.kernel.org" <linux-tegra@vger.kernel.org>
Subject: Re: [PATCH 1/3] staging:iio:magnetometer:ak8975 Don't use irq_to_gpio()
Date: Thu, 1 Sep 2011 18:20:25 +0200 [thread overview]
Message-ID: <201109011820.25307.arnd@arndb.de> (raw)
In-Reply-To: <74CDBE0F657A3D45AFBB94109FB122FF04B327A2A4@HQMAIL01.nvidia.com>
On Thursday 01 September 2011, Stephen Warren wrote:
> One question: When we add this field, how do drivers tell whether a value
> of 0 is an uninitialized field, or a legitimate GPIO value of 0? Should we
> add a flag to indicate validity, or just work hard to not enable driver-
> side code to use this value until we've fixed up all places that instantiate
> the driver to initialize the field to some invalid value like -1?
I think it's enough to coordinate the driver with the initialization of the
i2c data. If a driver requires a GPIO number, it can assume that it's valid.
Drivers that don't need one don't care. If it's an optional feature, you
might want to either use platform_data after all, or use different identifiers
for devices that have a gpio vs. those that have none -- in effect those are
different types of devices handled by the same driver.
Arnd
next prev parent reply other threads:[~2011-09-01 16:20 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-31 19:40 [PATCH 1/3] staging:iio:magnetometer:ak8975 Don't use irq_to_gpio() Stephen Warren
2011-08-31 19:40 ` [PATCH 2/3] staging:iio:magnetometer:ak8975: Don't assume 0 is an invalid GPIO Stephen Warren
2011-09-01 9:06 ` Jonathan Cameron
2011-08-31 19:40 ` [PATCH 3/3] staging:iio:magnetometer:ak8975: Fix probe() error-handling Stephen Warren
2011-09-01 9:08 ` Jonathan Cameron
2011-08-31 19:45 ` [PATCH 1/3] staging:iio:magnetometer:ak8975 Don't use irq_to_gpio() Andrew Chew
2011-09-01 9:01 ` Jonathan Cameron
2011-09-01 9:04 ` [PATCH] staging:iio:magnetometer:ak8975 use platform_data to pass the gpio number Jonathan Cameron
2011-09-01 11:06 ` [PATCH 1/3] staging:iio:magnetometer:ak8975 Don't use irq_to_gpio() Arnd Bergmann
2011-09-01 15:36 ` Stephen Warren
2011-09-01 16:20 ` Arnd Bergmann [this message]
2011-09-01 9:07 ` Jonathan Cameron
2011-09-01 9:24 ` Jonathan Cameron
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