From: broonie@opensource.wolfsonmicro.com (Mark Brown)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 6/6 v14] gpio: Add block gpio to several gpio drivers
Date: Thu, 24 Jan 2013 20:17:30 +0800 [thread overview]
Message-ID: <20130124121726.GQ4955@opensource.wolfsonmicro.com> (raw)
In-Reply-To: <CAOY=C6H5xETt5UNXUfRkGW9q+bj0y2R3sXNvW87XXvQcYoL_-g@mail.gmail.com>
On Thu, Jan 24, 2013 at 01:02:38PM +0100, Stijn Devriendt wrote:
> As a fictive example, consider the i2c-bitbang driver, which you could optimize
> by using block-gpio with sda/scl in a single block. By offering the
> block-gpio API
> even when you cannot set all bits at once, you could cause timing issues.
> You might be toggling the clock line before pushing out data, for example.
> The same holds below, for a driver that has separate hi/lo bits.
If there's a strict ordering requirement on updates then I would expect
a user to explictly code that in hardware otherwise there may be
hardware level issues with unpredictable results; besides in general it
seems silly to force users to open code both versions if they don't want
to rely on this API.
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From: Mark Brown <broonie@opensource.wolfsonmicro.com>
To: Stijn Devriendt <highguy@gmail.com>
Cc: Roland Stigge <stigge@antcom.de>,
gregkh@linuxfoundation.org, grant.likely@secretlab.ca,
linus.walleij@linaro.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, w.sang@pengutronix.de,
jbe@pengutronix.de, plagnioj@jcrosoft.com, daniel-gl@gmx.net,
rmallon@gmail.com, sr@denx.de, wg@grandegger.com,
mark.rutland@arm.com, nicolas.ferre@atmel.com
Subject: Re: [PATCH 6/6 v14] gpio: Add block gpio to several gpio drivers
Date: Thu, 24 Jan 2013 20:17:30 +0800 [thread overview]
Message-ID: <20130124121726.GQ4955@opensource.wolfsonmicro.com> (raw)
In-Reply-To: <CAOY=C6H5xETt5UNXUfRkGW9q+bj0y2R3sXNvW87XXvQcYoL_-g@mail.gmail.com>
[-- Attachment #1: Type: text/plain, Size: 760 bytes --]
On Thu, Jan 24, 2013 at 01:02:38PM +0100, Stijn Devriendt wrote:
> As a fictive example, consider the i2c-bitbang driver, which you could optimize
> by using block-gpio with sda/scl in a single block. By offering the
> block-gpio API
> even when you cannot set all bits at once, you could cause timing issues.
> You might be toggling the clock line before pushing out data, for example.
> The same holds below, for a driver that has separate hi/lo bits.
If there's a strict ordering requirement on updates then I would expect
a user to explictly code that in hardware otherwise there may be
hardware level issues with unpredictable results; besides in general it
seems silly to force users to open code both versions if they don't want
to rely on this API.
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next prev parent reply other threads:[~2013-01-24 12:17 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-22 12:06 [PATCH 0/6 v14] gpio: Add block GPIO Roland Stigge
2013-01-22 12:06 ` Roland Stigge
2013-01-22 12:06 ` [PATCH 1/6 v14] gpio: Add a block GPIO API to gpiolib Roland Stigge
2013-01-22 12:06 ` Roland Stigge
2013-01-27 13:19 ` Stijn Devriendt
2013-01-27 13:19 ` Stijn Devriendt
2013-01-27 13:58 ` Roland Stigge
2013-01-27 13:58 ` Roland Stigge
2013-01-28 11:30 ` Stijn Devriendt
2013-01-28 11:30 ` Stijn Devriendt
2013-01-31 20:56 ` Linus Walleij
2013-01-31 20:56 ` Linus Walleij
2013-01-22 12:06 ` [PATCH 2/6 v14] gpio: Add sysfs support to block GPIO API Roland Stigge
2013-01-22 12:06 ` Roland Stigge
2013-01-22 12:06 ` [PATCH 3/6 v14] gpio: Add userland device interface to block GPIO Roland Stigge
2013-01-22 12:06 ` Roland Stigge
2013-01-23 1:03 ` Jonathan Corbet
2013-01-23 1:03 ` Jonathan Corbet
2013-01-23 18:47 ` Roland Stigge
2013-01-23 18:47 ` Roland Stigge
2013-01-24 9:13 ` Alexander Stein
2013-01-24 9:13 ` Alexander Stein
2013-01-22 12:06 ` [PATCH 4/6 v14] gpiolib: Fix default attributes for class Roland Stigge
2013-01-22 12:06 ` Roland Stigge
2013-01-22 12:06 ` [PATCH 5/6 v14] gpio: Add device tree support to block GPIO API Roland Stigge
2013-01-22 12:06 ` Roland Stigge
2013-01-27 13:07 ` Stijn Devriendt
2013-01-27 13:07 ` Stijn Devriendt
2013-01-27 14:29 ` Roland Stigge
2013-01-27 14:29 ` Roland Stigge
2013-01-28 11:39 ` Stijn Devriendt
2013-01-28 11:39 ` Stijn Devriendt
2013-01-28 12:29 ` Roland Stigge
2013-01-28 12:29 ` Roland Stigge
2013-01-22 12:06 ` [PATCH 6/6 v14] gpio: Add block gpio to several gpio drivers Roland Stigge
2013-01-22 12:06 ` Roland Stigge
2013-01-24 12:02 ` Stijn Devriendt
2013-01-24 12:02 ` Stijn Devriendt
2013-01-24 12:17 ` Mark Brown [this message]
2013-01-24 12:17 ` Mark Brown
2013-01-24 12:19 ` Roland Stigge
2013-01-24 12:19 ` Roland Stigge
2013-01-27 12:18 ` Stijn Devriendt
2013-01-27 12:18 ` Stijn Devriendt
2013-01-27 13:48 ` Roland Stigge
2013-01-27 13:48 ` Roland Stigge
2013-01-28 11:27 ` Stijn Devriendt
2013-01-28 11:27 ` Stijn Devriendt
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