linux-kernel - Re: [PATCH 1/2] usb: typec: tps6598x: add reset gpio support

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Date:   Fri, 15 Sep 2023 12:03:28 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Bryan O'Donoghue <bryan.odonoghue@...aro.org>,
        Javier Carrasco <javier.carrasco@...fvision.net>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH 1/2] usb: typec: tps6598x: add reset gpio support

On 15/09/2023 11:52, Bryan O'Donoghue wrote:
>> +	struct gpio_desc *reset;
>>   	struct typec_port *port;
>>   	struct typec_partner *partner;
>>   	struct usb_pd_identity partner_identity;
>> @@ -717,6 +722,13 @@ static int tps6598x_probe(struct i2c_client *client)
>>   	mutex_init(&tps->lock);
>>   	tps->dev = &client->dev;
>>   
>> +	tps->reset = devm_gpiod_get_optional(tps->dev, "reset", GPIOD_OUT_LOW);
>> +	if (IS_ERR(tps->reset))
>> +		return dev_err_probe(tps->dev, PTR_ERR(tps->reset),
>> +				     "failed to get reset GPIO\n");
>> +	if (tps->reset)
>> +		msleep(SETUP_MS);
>> +
> 
> This looks a bit odd to me, shouldn't you drive reset to zero ?
> 
> if (tps->reset) {
>      gpiod_set_value_cansleep(tps->reset, 0);

It is driven by GPIOD_OUT_LOW.

>      msleep(SETUP_MS);
> }
> 
> also wouldn't it make sense to functionally decompose that and reuse in 
> probe() and tps6598x_resume() ?
> 
> tps6598x_reset() {
>      if (tps->reset) {
>          gpiod_set_value_cansleep(tps->reset, 0);
>          msleep(SETUP_MS);
>      }
> }


Best regards,
Krzysztof