linux-kernel - Re: [PATCH v5 3/3] iio: chemical: bme680: add power management

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <Z04aJg7eoBR9CYKe@vamoirid-laptop>
Date: Mon, 2 Dec 2024 21:35:50 +0100
From: Vasileios Amoiridis <vassilisamir@...il.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: jic23@...nel.org, lars@...afoo.de, robh@...nel.org, krzk+dt@...nel.org,
	conor+dt@...nel.org, u.kleine-koenig@...gutronix.de,
	linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 3/3] iio: chemical: bme680: add power management

On Mon, Dec 02, 2024 at 09:43:36PM +0200, Andy Shevchenko wrote:
> On Mon, Dec 02, 2024 at 08:23:41PM +0100, Vasileios Amoiridis wrote:
> > Add runtime power management to the device.
> 
> ...
> 
> > +	ret = pm_runtime_resume_and_get(dev);
> > +	if (ret)
> > +		return ret;
> > +
> > +	ret = __bme680_read_raw(indio_dev, chan, val, val2, mask);
> > +	pm_runtime_mark_last_busy(dev);
> > +	pm_runtime_put_autosuspend(dev);
> 
> Side note: as long as idle method is not defined (NULL) the above dance is
> already taken into account in the regular put.
> 
> ...
> 

Hi Andy,

Thanks again for the review! Indeed by looking at the code a bit, it
looks like the suspend callback is being called if the idle one is not
found. But I have seen this dance that you mention much more often in
the IIO that's why I used it. We can see what Jonathan has to say as
well, I think what you propose, simplifies things.

> > +static int bme680_buffer_preenable(struct iio_dev *indio_dev)
> > +{
> > +	struct bme680_data *data = iio_priv(indio_dev);
> > +	struct device *dev = regmap_get_device(data->regmap);
> > +	int ret;
> 
> > +	ret = pm_runtime_resume_and_get(dev);
> > +	if (ret)
> > +		return ret;
> > +
> > +	return 0;
> 
> Either this is broken (if the above can return positive codes), or can be
> replaced with direct return:
> 
> 	return pm_...
> 
> (but I believe it's the former and you wanted something like if (ret < 0)
>  there).
> 
> > +}
> 

Well, pm_runtime_resume_and_get() looks like it returns 0 on success and
negative value on error so I think the if (ret) is correct, no? But I
agree with you that it can be simplified as you proposed.

Cheers,
Vasilis

> -- 
> With Best Regards,
> Andy Shevchenko
> 
>