linux-kernel - Re: [PATCH 2/2] i2c: mv64xxx: add an optional reset-gpios property

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Message-ID: <20231012102140.kydfi2tppvhd7bdn@zenone.zhora.eu>
Date:   Thu, 12 Oct 2023 12:21:40 +0200
From:   Andi Shyti <andi.shyti@...nel.org>
To:     Chris Packham <chris.packham@...iedtelesis.co.nz>
Cc:     gregory.clement@...tlin.com, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        linux-i2c@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] i2c: mv64xxx: add an optional reset-gpios property

Hi Chris,

...

>  static struct mv64xxx_i2c_regs mv64xxx_i2c_regs_mv64xxx = {
> @@ -1083,6 +1084,10 @@ mv64xxx_i2c_probe(struct platform_device *pd)
>  	if (drv_data->irq < 0)
>  		return drv_data->irq;
>  
> +	drv_data->reset_gpio = devm_gpiod_get_optional(&pd->dev, "reset", GPIOD_OUT_HIGH);
> +	if (IS_ERR(drv_data->reset_gpio))
> +		return PTR_ERR(drv_data->reset_gpio);

if this optional why are we returning in case of error?

> +
>  	if (pdata) {
>  		drv_data->freq_m = pdata->freq_m;
>  		drv_data->freq_n = pdata->freq_n;
> @@ -1121,6 +1126,12 @@ mv64xxx_i2c_probe(struct platform_device *pd)
>  			goto exit_disable_pm;
>  	}
>  
> +	if (drv_data->reset_gpio) {
> +		udelay(1);
> +		gpiod_set_value_cansleep(drv_data->reset_gpio, 0);
> +		udelay(1);

you like busy waiting :-)

What is the reason behind these waits? Is there anything
specified by the datasheet?

If not I would do a more relaxed sleeping like an usleep_range...
what do you think?

Andi