linux-kernel - Re: [PATCH v11 8/8] iio: adc: ad4851: add ad485x driver

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Message-ID: <b06f6457-4be3-4404-8c41-618bad0c7099@baylibre.com>
Date: Thu, 6 Feb 2025 10:22:58 -0600
From: David Lechner <dlechner@...libre.com>
To: "Miclaus, Antoniu" <Antoniu.Miclaus@...log.com>,
 "jic23@...nel.org" <jic23@...nel.org>, "robh@...nel.org" <robh@...nel.org>,
 "conor+dt@...nel.org" <conor+dt@...nel.org>,
 "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
 "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 "linux-pwm@...r.kernel.org" <linux-pwm@...r.kernel.org>
Subject: Re: [PATCH v11 8/8] iio: adc: ad4851: add ad485x driver

On 2/6/25 4:00 AM, Miclaus, Antoniu wrote:
>> On 1/27/25 4:57 AM, Antoniu Miclaus wrote:
>>> Add support for the AD485X a fully buffered, 8-channel simultaneous
>>> sampling, 16/20-bit, 1 MSPS data acquisition system (DAS) with
>>> differential, wide common-mode range inputs.
>>>
>>> Signed-off-by: Antoniu Miclaus <antoniu.miclaus@...log.com>
>>> ---
>>
>> I think we have the important bits sorted now (i.e. userspace-facing stuff).
>> Just noticed a few minor things in the latest revision.
>>
>>
>>> +static int ad4851_setup(struct ad4851_state *st)
>>> +{
>>> +	unsigned int product_id;
>>> +	int ret;
>>> +
>>> +	if (st->pd_gpio) {
>>> +		/* To initiate a global reset, bring the PD pin high twice */
>>> +		gpiod_set_value(st->pd_gpio, 1);
>>> +		fsleep(1);
>>> +		gpiod_set_value(st->pd_gpio, 0);
>>> +		fsleep(1);
>>> +		gpiod_set_value(st->pd_gpio, 1);
>>> +		fsleep(1);
>>> +		gpiod_set_value(st->pd_gpio, 0);
>>> +		fsleep(1000);
>>> +	} else {
>>> +		ret = regmap_set_bits(st->regmap,
>> AD4851_REG_INTERFACE_CONFIG_A,
>>> +				      AD4851_SW_RESET);
>>> +		if (ret)
>>> +			return ret;
>>
>> Do we also need fsleep() after software reset?
> The datasheet doesn't mention any delay required after performing Software Reset.
> Should I add something just as a safety measure?

I guess it is probably OK if the datasheet doesn't say it needs a delay.