linux-kernel - Re: [RFC v4 09/10] pwm: dwc: add snps,pwm-number to limit pwm count

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Message-ID: <20220914165405.ae5nfi5336nsttkc@pengutronix.de>
Date:   Wed, 14 Sep 2022 18:54:05 +0200
From:   Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
To:     Ben Dooks <ben.dooks@...ive.com>
Cc:     linux-pwm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, Lee Jones <lee.jones@...aro.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Greentime Hu <greentime.hu@...ive.com>,
        jarkko.nikula@...ux.intel.com,
        William Salmon <william.salmon@...ive.com>,
        Jude Onyenegecha <jude.onyenegecha@...ive.com>
Subject: Re: [RFC v4 09/10] pwm: dwc: add snps,pwm-number to limit pwm count

On Tue, Aug 16, 2022 at 10:14:53PM +0100, Ben Dooks wrote:
> Add snps,pwm-number property to indicate if the block does not have
> all 8 of the PWM blocks.
> 
> Not sure if this should be a general PWM property consider optional
> for all PWM types, so have added a specific one here (there is only
> one other controller with a property for PWM count at the moment)
> 
> Signed-off-by: Ben Dooks <ben.dooks@...ive.com>
> ---
>  drivers/pwm/pwm-dwc-of.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/pwm/pwm-dwc-of.c b/drivers/pwm/pwm-dwc-of.c
> index d18fac287325..65c7e6621bba 100644
> --- a/drivers/pwm/pwm-dwc-of.c
> +++ b/drivers/pwm/pwm-dwc-of.c
> @@ -21,12 +21,20 @@ static int dwc_pwm_plat_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
>  	struct dwc_pwm *dwc;
> +	u32 nr_pwm;
>  	int ret;
>  
>  	dwc = dwc_pwm_alloc(dev);
>  	if (!dwc)
>  		return -ENOMEM;
>  
> +	if (!device_property_read_u32(dev, "snps,pwm-number", &nr_pwm)) {
> +		if (nr_pwm > DWC_TIMERS_TOTAL)
> +			dev_err(dev, "too many PWMs specified (%d)\n", nr_pwm);

Maybe

	dev_err(dev, "too many PWMs specified (%d), falling back to " #DWC_TIMERS_TOTAL "\n", nr_pwm);

to make it obvious the error doesn't prevent probing the device.

Or you believe the dtb and use whatever it specifies.

> +		else
> +			dwc->chip.npwm = nr_pwm;
> +	}
> +
>  	dwc->base = devm_platform_ioremap_resource(pdev, 0);
>  	if (IS_ERR(dwc->base))
>  		return dev_err_probe(dev, PTR_ERR(dwc->base),

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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