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 <20220825104422.14156-6-henning.schild@siemens.com> <20220825193340.058fd4c5@md1za8fc.ad001.siemens.net>
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From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Thu, 25 Aug 2022 21:03:53 +0300
Message-ID: <CAHp75Vd7jrPUb0bOdySDLmJQCdo6qieBaDVkTjf=u7R+Jyiv+g@mail.gmail.com>
Subject: Re: [PATCH v6 5/7] leds: simatic-ipc-leds-gpio: add new model 227G
To:     Henning Schild <henning.schild@siemens.com>
Cc:     Linus Walleij <linus.walleij@linaro.org>,
        Bartosz Golaszewski <brgl@bgdev.pl>,
        Pavel Machek <pavel@ucw.cz>,
        Hans de Goede <hdegoede@redhat.com>,
        Mark Gross <markgross@kernel.org>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Lee Jones <lee@kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux LED Subsystem <linux-leds@vger.kernel.org>,
        Platform Driver <platform-driver-x86@vger.kernel.org>,
        Sheng-Yuan Huang <syhuang3@nuvoton.com>,
        Tasanakorn Phaipool <tasanakorn@gmail.com>,
        simon.guinot@sequanux.org
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On Thu, Aug 25, 2022 at 8:51 PM Henning Schild
<henning.schild@siemens.com> wrote:
> Am Thu, 25 Aug 2022 12:44:20 +0200
> schrieb Henning Schild <henning.schild@siemens.com>:

...

> Concerning these two tables from above i have a question i need to find
> an answer for for maintaining the out-of-tree modules of these drivers.
>
> When getting the drivers into the kernel i had to rename the leds but
> in out-of-tree i would like to keep the old names and just equip their
> setters/getters with a deprecation warning. Just to give existing
> users time to slowly adopt the upstream name change if i can.
>
> In the open-coded way i just defined each LED twice and added a strcmp
> + pr_warn. With the "leds-gpio" version i still fail to find a solution
> which does not get me into -EBUSY. So i already fail at the second
> definition of the legacy name, not even had a chance to think about how
> to smuggle in my deprecation warning.
>
> I know out-of-tree is not a concern to people here, but someone might
> have an answer anyhow.

Yes, we (upstream) don't care about out-of-tree stuff. But I think
what you are asking for is kinda an alias. Maybe you simply can create
a module that will wait for the led appearing (by notify that adds a
device or alike) and create an alias by sysfs symlink (IIRC there are
kernel APIs for that)? It will be another out-of-tree module that you
may drop whenever is time.

-- 
With Best Regards,
Andy Shevchenko