linux-kernel - Re: [RESEND PATCH v8 06/10] serial: sc16is7xx: fix regression with GPIO configuration

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Date:   Mon, 24 Jul 2023 11:54:28 -0400
From:   Hugo Villeneuve <hugo@...ovil.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        jirislaby@...nel.org, jringle@...dpoint.com,
        isaac.true@...onical.com, jesse.sung@...onical.com,
        tomasz.mon@...lingroup.com, l.perczak@...lintechnologies.com,
        linux-serial@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org,
        Hugo Villeneuve <hvilleneuve@...onoff.com>,
        stable@...r.kernel.org,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Lech Perczak <lech.perczak@...lingroup.com>
Subject: Re: [RESEND PATCH v8 06/10] serial: sc16is7xx: fix regression with
 GPIO configuration

On Sat, 22 Jul 2023 17:15:26 +0200
Greg KH <gregkh@...uxfoundation.org> wrote:

> On Sat, Jul 22, 2023 at 10:47:24AM -0400, Hugo Villeneuve wrote:
> > On Fri, 21 Jul 2023 13:24:19 -0600
> > Rob Herring <robh+dt@...nel.org> wrote:
> > 
> > > On Fri, Jul 21, 2023 at 10:19 AM Hugo Villeneuve <hugo@...ovil.com> wrote:
> > > >
> > > > From: Hugo Villeneuve <hvilleneuve@...onoff.com>
> > > >
> > > > Commit 679875d1d880 ("sc16is7xx: Separate GPIOs from modem control lines")
> > > > and commit 21144bab4f11 ("sc16is7xx: Handle modem status lines")
> > > > changed the function of the GPIOs pins to act as modem control
> > > > lines without any possibility of selecting GPIO function.
> > > 
> > > Requiring a new DT property is not fixing a kernel regression. You
> > > should be returning the kernel to original behavior and then have a
> > > new DT property for new behavior.
> > 
> > Hi Rob,
> > please read the entire patch history starting from V1
> >  and you will understand why this course of action was
> >  not selected.
> 
> That's not going to happen, sorry, you need to explain it here, in this
> patch series, why a specific action is being taken over another one, as
> no one has time to go dig through past history, sorry.

Hi Rob,
I initially submitted a patch to revert the kernel to original
behavior, but it created more problems because the patch was
unfortunately split in two separate patches, and mixed with other non
closely-related changes. It was also noted to me that reverting to the
old behavior would break things for some users.

It was suggested to me by a more experienced kernel developer to
"suggest a fix, instead of hurrying a revert":

    https://lkml.org/lkml/2023/5/17/758

That is what we decided to do in the end, and it worked quite well.

Hugo.