Re: [PATCH] Input: adp5588-keys: Remove unused driver

["Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>]

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Hello Michael,

On Thu, May 05, 2022 at 06:20:22AM +0000, Hennerich, Michael wrote:
> > -----Original Message-----
> > From: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> > Sent: Mittwoch, 4. Mai 2022 10:46
> > To: Dmitry Torokhov <dmitry.torokhov@gmail.com>; Hennerich, Michael
> > <Michael.Hennerich@analog.com>
> > Cc: linux-input@vger.kernel.org; kernel@pengutronix.de; Arnd Bergmann
> > <arnd@arndb.de>
> > Subject: [PATCH] Input: adp5588-keys: Remove unused driver
> > 
> > The last user is gone since 2018 (commit 4ba66a976072 ("arch: remove
> > blackfin port")). This is an i2c driver, so it could be used on a non-blackfin
> > machine, but this driver requires platform data, so it cannot be bound using
> > device tree.
> 
> Hi Uwe,
> 
> If we start removing drivers which obviously don't have a mainline in-tree user,
> we would upset up many users of these drivers.
> I agree on updating this driver to make platform data optional.
> We could provide a patch in a few days.

Just to add some background why I stumbled over this driver: On of my
current quests is to make i2c remove callbacks return void. As a
preparation for that I work on updating all i2c drivers to return 0 in
.remove() to make the change to void have no side effects.

One of the offenders is drivers/gpio/gpio-adp5588.c, which in the
presence of a pdata->teardown callback might return a non-zero value
from .remove(). While looking at the pdata of possible devices I only
found drivers/input/keyboard/adp5588-keys.c.

So the options for my quest are in increasing impact order:

 a) just warn if struct adp5588_gpio_platform_data::teardown fails and
    still return 0 from .remove()
 b) make struct adp5588_gpio_platform_data::teardown return void
 c) drop teardown support from adp5588_gpio_platform_data
 d) drop platform support from gpio-adp5588
 e) drop gpio-adp5588

Currently I'd go for at least d).

Having said that I think e) has a net benefit. If there is no user left
it reduces maintainance burden. If there is a user left, they hopefully
will tell us, we can restore the driver from git history and then at
least know a tester for future cleanups and changes.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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