linux-kernel - Re: [PATCH v4 13/14] pwm: jz4740: Let the pinctrl driver configure the pins

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Message-ID: <20170406144034.GE8438@ulmo.ba.sec>
Date:   Thu, 6 Apr 2017 16:40:34 +0200
From:   Thierry Reding <thierry.reding@...il.com>
To:     Paul Cercueil <paul@...pouillou.net>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Alexandre Courbot <gnurou@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Boris Brezillon <boris.brezillon@...e-electrons.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Maarten ter Huurne <maarten@...ewalker.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Paul Burton <paul.burton@...tec.com>, james.hogan@...tec.com,
        linux-gpio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mips@...ux-mips.org,
        linux-mmc@...r.kernel.org, linux-mtd@...ts.infradead.org,
        linux-pwm@...r.kernel.org, linux-fbdev@...r.kernel.org
Subject: Re: [PATCH v4 13/14] pwm: jz4740: Let the pinctrl driver configure
 the pins

On Sun, Apr 02, 2017 at 10:42:43PM +0200, Paul Cercueil wrote:
> Now that the JZ4740 and similar SoCs have a pinctrl driver, we rely on
> the pins being properly configured before the driver probes.
> 
> One inherent problem of this new approach is that the pinctrl framework
> does not allow us to configure each pin on demand, when the various PWM
> channels are requested or released. For instance, the PWM channels can
> be configured from sysfs, which would require all PWM pins to be configured
> properly beforehand for the PWM function, eventually causing conflicts
> with other platform or board drivers.
> 
> The proper solution here would be to modify the pwm-jz4740 driver to
> handle only one PWM channel, and create an instance of this driver
> for each one of the 8 PWM channels. Then, it could use the pinctrl
> framework to dynamically configure the PWM pin it controls.
> 
> Until this can be done, the only jz4740 board supported upstream
> (Qi lb60) can configure all of its connected PWM pins in PWM function
> mode, since those are not used by other drivers nor by GPIOs on the
> board.
> 
> Signed-off-by: Paul Cercueil <paul@...pouillou.net>
> ---
>  drivers/pwm/pwm-jz4740.c | 29 -----------------------------
>  1 file changed, 29 deletions(-)

Assuming that you want to take this through the pinctrl tree along with
the remainder of the series:

Acked-by: Thierry Reding <thierry.reding@...il.com>

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