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

["Hennerich, Michael" <Michael.Hennerich@analog.com>]

> -----Original Message-----
> From: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> Sent: Donnerstag, 5. Mai 2022 09:50
> To: Hennerich, Michael <Michael.Hennerich@analog.com>
> Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>; Bogdan, Dragos
> <Dragos.Bogdan@analog.com>; Sa, Nuno <Nuno.Sa@analog.com>; Arnd
> Bergmann <arnd@arndb.de>; kernel@pengutronix.de; linux-
> input@vger.kernel.org
> Subject: Re: [PATCH] Input: adp5588-keys: Remove unused driver
> 
> 
> 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.

Hi Uwe,

Thanks for the explanation.

I know that there are users of this driver. But I admit, we should have earlier
made platform_data support optional and also add proper dt bindings.
We're in progress doing so. And in the meanwhile, I would prefer a less
disruptive intermediate change. For example c) with the promise we're working on d).

Best regards,
Michael

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