linux-kernel - Re: [PATCH v4] leds: simatic-ipc-leds-gpio: make sure we have the GPIO providing driver

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Date:   Fri, 3 Feb 2023 17:58:04 +0100
From:   Henning Schild <henning.schild@...mens.com>
To:     Lee Jones <lee@...nel.org>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Pavel Machek <pavel@....cz>, linux-leds@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Andy Shevchenko <andy.shevchenko@...il.com>
Subject: Re: [PATCH v4] leds: simatic-ipc-leds-gpio: make sure we have the
 GPIO providing driver

Am Fri, 3 Feb 2023 07:59:04 +0000
schrieb Lee Jones <lee@...nel.org>:

> On Thu, 02 Feb 2023, Henning Schild wrote:
> 
> > Am Thu, 19 Jan 2023 21:02:40 +0000
> > schrieb Lee Jones <lee@...nel.org>:
> >   
> > > On Fri, 07 Oct 2022, Henning Schild wrote:
> > >   
> > > > If we register a "leds-gpio" platform device for GPIO pins that
> > > > do not exist we get a -EPROBE_DEFER and the probe will be tried
> > > > again later. If there is no driver to provide that pin we will
> > > > poll forever and also create a lot of log messages.
> > > > 
> > > > So check if that GPIO driver is configured, if so it will come
> > > > up eventually. If not, we exit our probe function early and do
> > > > not even bother registering the "leds-gpio". This method was
> > > > chosen over "Kconfig depends" since this way we can add support
> > > > for more devices and GPIO backends more easily without
> > > > "depends":ing on all GPIO backends.
> > > > 
> > > > Fixes: a6c80bec3c93 ("leds: simatic-ipc-leds-gpio: Add GPIO
> > > > version of Siemens driver") Reviewed-by: Andy Shevchenko
> > > > <andy.shevchenko@...il.com> Signed-off-by: Henning Schild
> > > > <henning.schild@...mens.com> ---
> > > >  drivers/leds/simple/simatic-ipc-leds-gpio.c | 2 ++
> > > >  1 file changed, 2 insertions(+)    
> > > 
> > > FYI: I'm going to try my best not to take another one like this.  
> > 
> > You will not have to. I now understood how to improve on that as i
> > am adding more variants needing more gpio controller drivers.
> >   
> > > Please try to improve the whole situation for you next submission.
> > > 
> > > Applied, thanks.  
> > 
> > I hope this is still in the branches for a merge. It should be
> > applied. It does fix a problem but using a wrong pattern, but a
> > pattern that is already in use.  
> 
> What makes you think it's not applied?

Because i had that other one potentially replacing it so it was maybe
called off. Good to know it was not stopped.

Henning

>  
> > So this will fix 6.1 and above in the short term.
> > 
> > In the long term i will restructure to individual drivers which
> > have a clear dependency chain in Kconfig. I will use inheritance to
> > arrive at minimal code duplication and will use Kconfig switch
> > default inheritance to ease configuration.
> > 
> > Such restructuring patches will have to be written first, but they
> > will come. Either stand-alone or together with the next machine.  
> 
> That's fine.  Whatever suits.
>