linux-kernel - Re: [PATCH v13 03/10] mux: minimal mux subsystem and gpio-based mux controller

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Date:   Fri, 5 May 2017 15:19:48 +0200
From:   Peter Rosin <peda@...ntia.se>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:     <linux-kernel@...r.kernel.org>, Wolfram Sang <wsa@...-dreams.de>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Jonathan Corbet <corbet@....net>, <linux-i2c@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-iio@...r.kernel.org>,
        <linux-doc@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Colin Ian King <colin.king@...onical.com>,
        Paul Gortmaker <paul.gortmaker@...driver.com>,
        Philipp Zabel <p.zabel@...gutronix.de>, <kernel@...gutronix.de>
Subject: Re: [PATCH v13 03/10] mux: minimal mux subsystem and gpio-based mux
 controller

On 2017-04-18 12:59, Peter Rosin wrote:
> On 2017-04-18 10:51, Greg Kroah-Hartman wrote:
>> On Thu, Apr 13, 2017 at 06:43:07PM +0200, Peter Rosin wrote:
>>> +/**
>>> + * devm_mux_chip_unregister() - Resource-managed version mux_chip_unregister().
>>> + * @dev: The device that originally registered the mux-chip.
>>> + * @mux_chip: The mux-chip to unregister.
>>> + *
>>> + * See mux_chip_unregister() for more details.
>>> + *
>>> + * Note that you do not normally need to call this function.
>>
>> Odd, then why is it exported???
> 
> You normally don't call the devm_foo_{free,release,unregister,etc} functions.
> The intention is of course that the resourse cleans up automatically. But there
> are no cases where the manual clean up is not available, at least not that I can
> find?

I had a second look and there are of course plenty of examples of missing clean up
versions for devm function. I simply hadn't looked very hard at all.

So, for v15 I intend to remove all of devm_mux_chip_unregister, devm_mux_chip_free
and devm_mux_control_put. They are all just sitting there with no callers. And the
mux-mmio/video-mux drivers by Philipp Zabel that build on top of this series don't
need them either. Besides, easy to resurrect if needed...

I will do v15 with the above, the change from mutex to semaphore for locking the
mux controller state [1] and a few small documentation improvements. That will be
rebased onto v4.12-rc1 and sent in 10 days or so, or whenever v4.12-rc1 is out.

Meanwhile, what I currently intend for v15 but based on v4.11 is available from
https://gitlab.com/peda-linux/mux.git in the "mux" branch.

Cheers,
peda

[1] https://lkml.org/lkml/2017/4/25/411