From: Mark Brown <broonie@kernel.org>
To: Michael Walle <michael@walle.cc>
Cc: linux-kernel@vger.kernel.org, linux-gpio@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J . Wysocki" <rafael@kernel.org>,
Linus Walleij <linus.walleij@linaro.org>,
Bartosz Golaszewski <bgolaszewski@baylibre.com>,
Andy Shevchenko <andy.shevchenko@gmail.com>
Subject: Re: [PATCH 1/2] regmap: add regmap_might_sleep()
Date: Fri, 30 Apr 2021 18:26:03 +0100 [thread overview]
Message-ID: <20210430172603.GE5981@sirena.org.uk> (raw)
In-Reply-To: <df27a6508e9edcd8b56058ac4834fd56@walle.cc>
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On Fri, Apr 30, 2021 at 06:01:49PM +0200, Michael Walle wrote:
> Am 2021-04-30 17:19, schrieb Mark Brown:
> > Whatever is creating the regmap really ought to know what device it's
> > dealing with...
> But creating and using the regmap are two seperate things, no? Consider
> the gpio-sl28cpld. It will just use whatever regmap the parent has created.
> How would it know what type of regmap it is?
But that's a driver for a specific device AFAICT which looks like it's
only got an I2C binding on the MFD so the driver knows that it's for a
device that's on a bus that's going to sleep and doesn't need to infer
anything? This looks like the common case I'd expect where there's no
variation.
> > > It might be possible to pass this information via the
> > > gpio_regmap_config, but this has the following drawbacks. First, that
> > > property is redundant and both places might contratict each other. And
> > > secondly, the driver might not even know the type of the regmap
> > > because
> > > it just gets an opaque pointer by querying the device tree.
> > If it's a generic GPIO driver from a code correctness point of view it's
> > always got a risk of sleeping...
> I can't follow you here.
If users happen to end up with a map flagged as fast they can work on
the whatever driver uses this stuff and not realise they're breaking
other users of the same driver that end up with slow I/O. The whole
point of the flag in GPIO is AIUI warnings to help with that case.
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next prev parent reply other threads:[~2021-04-30 17:26 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-30 13:06 [PATCH 1/2] regmap: add regmap_might_sleep() Michael Walle
2021-04-30 13:06 ` [PATCH 2/2] gpio: regmap: use new regmap_might_sleep() Michael Walle
2021-04-30 15:19 ` [PATCH 1/2] regmap: add regmap_might_sleep() Mark Brown
2021-04-30 16:01 ` Michael Walle
2021-04-30 17:26 ` Mark Brown [this message]
2021-04-30 22:10 ` Michael Walle
2021-05-06 12:43 ` Mark Brown
2021-05-06 13:35 ` Michael Walle
2021-05-06 15:53 ` Mark Brown
2022-11-21 15:08 Michael Walle
2022-11-22 19:43 ` Mark Brown
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