linux-kernel - Re: [PATCH v2 1/5] pinctrl: Allow modules to use pinctrl_[un]register

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Date:   Wed, 1 Jan 2020 14:04:29 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Ville Syrjälä <ville.syrjala@...ux.intel.com>,
        intel-gfx <intel-gfx@...ts.freedesktop.org>,
        Lee Jones <lee.jones@...aro.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        "open list:DRM PANEL DRIVERS" <dri-devel@...ts.freedesktop.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>
Subject: Re: [PATCH v2 1/5] pinctrl: Allow modules to use
 pinctrl_[un]register_mappings

Hi,

On 30-12-2019 14:31, Linus Walleij wrote:
> On Mon, Dec 16, 2019 at 9:51 PM Hans de Goede <hdegoede@...hat.com> wrote:
> 
>> Currently only the drivers/pinctrl/devicetree.c code allows registering
>> pinctrl-mappings which may later be unregistered, all other mappings
>> are assumed to be permanent.
>>
>> Non-dt platforms may also want to register pinctrl mappings from code which
>> is build as a module, which requires being able to unregister the mapping
>> when the module is unloaded to avoid dangling pointers.
>>
>> To allow unregistering the mappings the devicetree code uses 2 internal
>> functions: pinctrl_register_map and pinctrl_unregister_map.
>>
>> pinctrl_register_map allows the devicetree code to tell the core to
>> not memdup the mappings as it retains ownership of them and
>> pinctrl_unregister_map does the unregistering, note this only works
>> when the mappings where not memdupped.
>>
>> The only code relying on the memdup/shallow-copy done by
>> pinctrl_register_mappings is arch/arm/mach-u300/core.c this commit
>> replaces the __initdata with const, so that the shallow-copy is no
>> longer necessary.
>>
>> After that we can get rid of the internal pinctrl_unregister_map function
>> and just use pinctrl_register_mappings directly everywhere.
>>
>> This commit also renames pinctrl_unregister_map to
>> pinctrl_unregister_mappings so that its naming matches its
>> pinctrl_register_mappings counter-part and exports it.
>>
>> Together these 2 changes will allow non-dt platform code to
>> register pinctrl-mappings from modules without breaking things on
>> module unload (as they can now unregister the mapping on unload).
>>
>> Signed-off-by: Hans de Goede <hdegoede@...hat.com>
> 
> This v2 works fine for me, I applied it to this immutable branch in the
> pinctrl tree:
> https://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl.git/log/?h=ib-pinctrl-unreg-mappings
> 
> And pulled that into the pinctrl "devel" branch for v5.6.
> 
> Please pull this immutable branch into the Intel DRM tree and apply
> the rest of the stuff on top!

Great, thank you!

Regards,

Hans

p.s.

Happy New year everyone.