linux-kernel - Re: [PATCH 03/14] iio: adc: rzg2l_adc: Simplify the runtime PM code

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Message-ID: <d37b9776-0727-46b6-93f2-02fb7b58732f@bp.renesas.com>
Date: Tue, 3 Dec 2024 14:20:55 +0000
From: Paul Barker <paul.barker.ct@...renesas.com>
To: Claudiu Beznea <claudiu.beznea@...on.dev>,
 prabhakar.mahadev-lad.rj@...renesas.com, jic23@...nel.org, lars@...afoo.de,
 robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org,
 geert+renesas@...der.be, magnus.damm@...il.com, mturquette@...libre.com,
 sboyd@...nel.org, p.zabel@...gutronix.de
Cc: linux-iio@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-clk@...r.kernel.org, Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: Re: [PATCH 03/14] iio: adc: rzg2l_adc: Simplify the runtime PM code

Hi Claudiu,

On 03/12/2024 13:40, Claudiu Beznea wrote:
> On 03.12.2024 14:53, Paul Barker wrote:
>> On 03/12/2024 11:13, Claudiu wrote:
>>>  static int rzg2l_adc_conversion(struct iio_dev *indio_dev, struct rzg2l_adc *adc, u8 ch)
>>>  {
>>> +	struct device *dev = indio_dev->dev.parent;
>>>  	int ret;
>>>  
>>> -	ret = rzg2l_adc_set_power(indio_dev, true);
>>> +	ret = pm_runtime_resume_and_get(dev);
>>>  	if (ret)
>>>  		return ret;
>>
>> Should we check (ret < 0) here instead of just (ret)? According to the
>> docs [1], pm_runtime_resume_and_get() can return 1 if the device is
>> already active.
> 
> The v6.13-rc1 implementation of pm_runtime_resume_and_get() is:
> 
> static inline int pm_runtime_resume_and_get(struct device *dev)
> {
> 	int ret;
> 
> 	ret = __pm_runtime_resume(dev, RPM_GET_PUT);
> 	if (ret < 0) {
> 		pm_runtime_put_noidle(dev);
> 		return ret;
> 	}
> 
> 	return 0;
> }
> 
> It can return zero or negative error number.

Ah, ok. The docs say that pm_runtime_resume_and_get() will "return the
result of pm_runtime_resume" (which can return 1), but it doesn't do
that exactly. I'll send a fix for the docs.

Thanks,

-- 
Paul Barker
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