linux-kernel - Re: [PATCH v6] gpio: pca953x: Add Maxim MAX7313 PWM support

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Message-ID: <CAHp75Vehv_Cp1AhMPhk8ktyp-uHSkgweqnhhSq_7w2Kf9y=7XQ@mail.gmail.com>
Date:   Mon, 29 Jun 2020 19:50:41 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Miquel Raynal <miquel.raynal@...tlin.com>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Uwe Kleine-Konig <u.kleine-koenig@...gutronix.de>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        linux-pwm@...r.kernel.org,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6] gpio: pca953x: Add Maxim MAX7313 PWM support

On Mon, Jun 29, 2020 at 5:08 PM Miquel Raynal <miquel.raynal@...tlin.com> wrote:
> Miquel Raynal <miquel.raynal@...tlin.com> wrote on Sun,  3 May 2020
> 12:54:53 +0200:
>
> > The MAX7313 chip is fully compatible with the PCA9535 on its basic
> > functions but can also manage the intensity on each of its ports with
> > PWM. Each output is independent and may be tuned with 16 values (4
> > bits per output). The period is always 32kHz, only the duty-cycle may
> > be changed. One can use any output as GPIO or PWM.

> Can I have a status on this patch please?
>
> If it was forgotten, I would be good to have it queued now, otherwise,
> may I know the reason?

TWIMC, just my 2 cents about this patch.
I don't like it in this form. On the constructive side I can propose
at least two ways to solve:
a) introduce a PWM as a pin mode; move pca953x to pin control; use
this mode with PWM driver being separated from the pin control;
b) introduce an MFD that provides two parts for this GPIO & PWM.

Personally I would go with a) as I know at least one more pin
controller which will get an advantage of this (and it's definitely
not an MFD).

If GPIO / pin control maintainers consider this okay, I will rest my
case, but see above...

-- 
With Best Regards,
Andy Shevchenko