linux-kernel - Re: [PATCH v6 1/4] iio: pressure: bmp280: Use sleep and forced mode for oneshot captures

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Message-ID: <20240913235841.GB33362@vamoiridPC>
Date: Sat, 14 Sep 2024 01:58:41 +0200
From: Vasileios Amoiridis <vassilisamir@...il.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: Vasileios Amoiridis <vassilisamir@...il.com>, jic23@...nel.org,
	lars@...afoo.de, robh@...nel.org, krzk+dt@...nel.org,
	conor+dt@...nel.org, ang.iglesiasg@...il.com,
	linus.walleij@...aro.org, biju.das.jz@...renesas.com,
	javier.carrasco.cruz@...il.com, semen.protsenko@...aro.org,
	579lpy@...il.com, ak@...klinger.de, linux-iio@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	christophe.jaillet@...adoo.fr
Subject: Re: [PATCH v6 1/4] iio: pressure: bmp280: Use sleep and forced mode
 for oneshot captures

On Fri, Sep 13, 2024 at 12:51:55PM +0300, Andy Shevchenko wrote:
> On Fri, Sep 13, 2024 at 01:32:31AM +0200, Vasileios Amoiridis wrote:
> > Add forced mode support in sensors BMP28x, BME28x, BMP3xx and BMP58x.
> > Sensors BMP18x and BMP085 are old and do not support this feature so
> > their operation is not affected at all.
> > 
> > Essentially, up to now, the rest of the sensors were used in normal mode
> > all the time. This means that they are continuously doing measurements
> > even though these measurements are not used. Even though the sensor does
> > provide PM support, to cover all the possible use cases, the sensor needs
> > to go into sleep mode and wake up whenever necessary.
> > 
> > The idea is that the sensor is by default in sleep mode, wakes up in
> > forced mode when a oneshot capture is requested, or in normal mode
> > when the buffer is enabled. The difference lays in the fact that in
> > forced mode, the sensor does only one conversion and goes back to sleep
> > while in normal mode, the sensor does continuous measurements with the
> > frequency that was set in the ODR registers.
> > 
> > The bmpX_chip_config() functions which are responsible for applying
> > the requested configuration to the sensor, are modified accordingly
> > in order to set the sensor by default in sleep mode.
> > 
> > DEEP STANDBY, Low Power NORMAL and CONTINUOUS modes, supported only by
> > the BMP58x version, are not added.
> 
> ...
> 
> > +	if (!((reg & BMP380_STATUS_DRDY_PRESS_MASK) &&
> > +	    (reg & BMP380_STATUS_DRDY_TEMP_MASK))) {
> 
> I would add one more space to make the indentation follow the logic.
> 
> (no need to resend until Jonathan asks for it, otherwise I believe
>  he can amend this whilst applying)
> 
> > +		dev_err(data->dev, "Measurement cycle didn't complete.\n");
> > +		return -EBUSY;
> > +	}
> 
> ...
> 
> > +		/*
> > +		 * According to the BMP3 Sensor API, the sensor needs 5000us
> 
> Can we use 5ms...
> 
> > +		 * in order to go to the sleep mode.
> > +		 */
> > +		fsleep(5000);
> 
> ...and 5 * USEC_PER_MSEC here respectively?
> 
> -- 
> With Best Regards,
> Andy Shevchenko
> 
> 


Hi Andy,

Thanks for the time for the review once again. I think I can manage to
find the time to do it today.

Cheers,
Vasilis