Re: [PATCH v2 1/5] pinctrl: Allow modules to use pinctrl_[un]register_mappings

From: Jani Nikula <jani.nikula@linux.intel.com>
To: Linus Walleij <linus.walleij@linaro.org>,
	Hans de Goede <hdegoede@redhat.com>
Cc: "Joonas Lahtinen" <joonas.lahtinen@linux.intel.com>,
	"Rodrigo Vivi" <rodrigo.vivi@intel.com>,
	"Ville Syrjälä" <ville.syrjala@linux.intel.com>,
	intel-gfx <intel-gfx@lists.freedesktop.org>,
	"Lee Jones" <lee.jones@linaro.org>,
	"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
	"open list:DRM PANEL DRIVERS" <dri-devel@lists.freedesktop.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>
Subject: Re: [PATCH v2 1/5] pinctrl: Allow modules to use pinctrl_[un]register_mappings
Date: Thu, 02 Jan 2020 11:04:43 +0200	[thread overview]
Message-ID: <875zhuut3o.fsf@intel.com> (raw)
In-Reply-To: <CACRpkdaXFSJVkWJGzsVcvbUA9gpgP0Vbkwf1H-HWw8s35R9XYQ@mail.gmail.com>

On Mon, 30 Dec 2019, Linus Walleij <linus.walleij@linaro.org> wrote:
> On Mon, Dec 16, 2019 at 9:51 PM Hans de Goede <hdegoede@redhat.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@redhat.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!

Thanks, pulled to drm-intel-next-queued.

BR,
Jani.

-- 
Jani Nikula, Intel Open Source Graphics Center