linux-kernel - Re: [PATCH v7 2/2] pwm: sophgo: add pwm support for Sophgo CV1800 SoC

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Message-ID: <j74t2zqvoslo5fgmea4kp434tafgchkncytofj65zbbt7ivcqy@auboc3pkdiz3>
Date: Mon, 7 Apr 2025 15:21:59 +0800
From: Inochi Amaoto <inochiama@...il.com>
To: Thomas Bonnefille <thomas.bonnefille@...tlin.com>, 
	Uwe Kleine-König <ukleinek@...nel.org>, Jingbao Qiu <qiujingbao.dlmu@...il.com>
Cc: robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org, 
	unicorn_wang@...look.com, dlan@...too.org, linux-pwm@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 2/2] pwm: sophgo: add pwm support for Sophgo CV1800 SoC

On Sun, Apr 06, 2025 at 02:16:41AM +0200, Thomas Bonnefille wrote:
> Hello,
> 
> On Sat Jun 1, 2024 at 1:53 PM CEST, Uwe Kleine-König wrote:
> > On Wed, May 01, 2024 at 04:32:42PM +0800, Jingbao Qiu wrote:
> >> [...]
> >> +	if ((state & BIT(pwm->hwpwm)) && enable)
> >> +		regmap_update_bits(priv->map, PWM_CV1800_OE,
> >> +				   PWM_CV1800_OE_MASK(pwm->hwpwm),
> >> +				   PWM_CV1800_REG_ENABLE(pwm->hwpwm));
> >
> > This looks strange. If BIT(hwpwm) is already set, set it again?!
> > Also if you used the caching implemented in regmap, you don't need to
> > make this conditional.
> >
> 
> I was testing the series and noticed indeed an issue in this driver at
> those lines. If PWM_CV1800_OE isn't set by something else than the
> kernel it will never be set and so, there will never be a PWM outputted.
> 
> Using :
>     if (!(state & BIT(pwm->hwpwm)) && enable)
> Solved the issue but as Uwe said you can probably rely on regmap caching
> to avoid this condition.
> 
> >
> > ...
> > 
> 
> Do you plan on sending a new iteration some day ? I may have some time
> to continue the upstreaming process if you need to.
> 
> Thank you for this series !
> Thomas

I suggest checking existing spi-sg2044-nor driver, which may reduce your
work for upstreaming.

Regards,
Inochi