linux-kernel - Re: [PATCH 2/4] pwm: pca9685: remove ALL

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Date:   Mon, 30 Mar 2020 17:38:10 +0200
From:   Thierry Reding <thierry.reding@...il.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Matthias Schiffer <matthias.schiffer@...tq-group.com>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>, linux-pwm@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/4] pwm: pca9685: remove ALL_LED PWM channel

On Mon, Mar 30, 2020 at 04:19:55PM +0300, Andy Shevchenko wrote:
> On Mon, Mar 30, 2020 at 4:10 PM Thierry Reding <thierry.reding@...il.com> wrote:
> >
> > On Wed, Feb 26, 2020 at 02:52:27PM +0100, Matthias Schiffer wrote:
> > > The interaction of the ALL_LED PWM channel with the other channels was
> > > not well-defined. As the ALL_LED feature does not seem very useful and
> > > it was making the code significantly more complex, simply remove it.
> > >
> > > Signed-off-by: Matthias Schiffer <matthias.schiffer@...tq-group.com>
> > > ---
> > >  drivers/pwm/pwm-pca9685.c | 115 ++++++--------------------------------
> > >  1 file changed, 17 insertions(+), 98 deletions(-)
> >
> > Applied, thanks.
> 
> This seems to be ABI breakage.

Nothing seemed to be using that feature. As a matter of fact, I don't
really see anyone using this chip in an upstream kernel, so it's
difficult to understand what the dependencies are.

> Thierry, do you have hardware to test?

No, I don't. Do you?

Does anybody have a good understanding of where the users of this are
and where the code is? There seems to be a lot of confusion around this
driver/chip and how it's being used and it keeps causing a lot of this
back and forth, so can we please gather some basic information and then
I'll add that to the driver along with perhaps a list of contacts that
want to be involved.

As it is, it seems like applying patches as I see fit is the only way to
get people to object, which is a suboptimal way to do things. =)

Thierry

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