linux-kernel - Re: [PATCH v2 3/3] iio: adc: Fix polling of INA219 conversion ready flag

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Date:   Wed, 24 May 2017 20:56:54 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Stefan Brüns <stefan.bruens@...h-aachen.de>
Cc:     <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Marc Titinger <mtitinger@...libre.com>, afd@...com
Subject: Re: [PATCH v2 3/3] iio: adc: Fix polling of INA219 conversion ready
 flag

On Wed, 24 May 2017 20:53:35 +0100
Jonathan Cameron <jic23@...nel.org> wrote:

> On Wed, 24 May 2017 02:09:07 +0200
> Stefan Brüns <stefan.bruens@...h-aachen.de> wrote:
> 
> > While the INA226 has a conversion ready flag (CVRF) in the R/W Mask/Enable
> > register with read-to-clear semantics, the corresponding bit of the INA219
> > (CNVR) is part of the bus voltage register. The flag is cleared by reading
> > the power register.
> > 
> > Signed-off-by: Stefan Brüns <stefan.bruens@...h-aachen.de>  
> Again, looks good to me, but I would like input form Marc or Andrew
> who are more familiar with these devices than me!
> 
> Ping me in a week or two if nothing is happening and I look to have
> lost these!
Ah Marc's old email is bouncing.  If no one has a more up to
data address I guess we'll be looking at Andrew to have a chance to
respond (which is more likely if I actually cc him ;)
> 
> Thanks,
> 
> Jonathan
> > ---
> >  drivers/iio/adc/ina2xx-adc.c | 36 +++++++++++++++++++++++++++++-------
> >  1 file changed, 29 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c
> > index 232c0b80d658..68884d26b50c 100644
> > --- a/drivers/iio/adc/ina2xx-adc.c
> > +++ b/drivers/iio/adc/ina2xx-adc.c
> > @@ -44,6 +44,7 @@
> >  
> >  #define INA226_MASK_ENABLE		0x06
> >  #define INA226_CVRF			BIT(3)
> > +#define INA219_CNVR			BIT(1)
> >  
> >  #define INA2XX_MAX_REGISTERS            8
> >  
> > @@ -592,6 +593,7 @@ static int ina2xx_work_buffer(struct iio_dev *indio_dev)
> >  	int bit, ret, i = 0;
> >  	s64 time_a, time_b;
> >  	unsigned int alert;
> > +	int cnvr_need_clear = 0;
> >  
> >  	time_a = iio_get_time_ns(indio_dev);
> >  
> > @@ -603,22 +605,30 @@ static int ina2xx_work_buffer(struct iio_dev *indio_dev)
> >  	 * we check the ConVersionReadyFlag.
> >  	 * On hardware that supports using the ALERT pin to toggle a
> >  	 * GPIO a triggered buffer could be used instead.
> > -	 * For now, we pay for that extra read of the ALERT register
> > +	 * For now, we do an extra read of the MASK_ENABLE register (INA226)
> > +	 * resp. the BUS_VOLTAGE register (INA219).
> >  	 */
> >  	if (!chip->allow_async_readout)
> >  		do {
> > -			ret = regmap_read(chip->regmap, INA226_MASK_ENABLE,
> > -					  &alert);
> > +			if (chip->config->chip_id == ina226) {
> > +				ret = regmap_read(chip->regmap,
> > +						  INA226_MASK_ENABLE, &alert);
> > +				alert &= INA226_CVRF;
> > +			} else {
> > +				ret = regmap_read(chip->regmap,
> > +						  INA2XX_BUS_VOLTAGE, &alert);
> > +				alert &= INA219_CNVR;
> > +				cnvr_need_clear = alert;
> > +			}
> > +
> >  			if (ret < 0)
> >  				return ret;
> >  
> > -			alert &= INA226_CVRF;
> >  		} while (!alert);
> >  
> >  	/*
> > -	 * Single register reads: bulk_read will not work with ina226
> > -	 * as there is no auto-increment of the address register for
> > -	 * data length longer than 16bits.
> > +	 * Single register reads: bulk_read will not work with ina226/219
> > +	 * as there is no auto-increment of the register pointer.
> >  	 */
> >  	for_each_set_bit(bit, indio_dev->active_scan_mask,
> >  			 indio_dev->masklength) {
> > @@ -630,6 +640,18 @@ static int ina2xx_work_buffer(struct iio_dev *indio_dev)
> >  			return ret;
> >  
> >  		data[i++] = val;
> > +
> > +		if (INA2XX_SHUNT_VOLTAGE + bit == INA2XX_POWER)
> > +			cnvr_need_clear = 0;
> > +	}
> > +
> > +	/* Dummy read on INA219 power register to clear CNVR flag */
> > +	if (cnvr_need_clear && chip->config->chip_id == ina219) {
> > +		unsigned int val;
> > +
> > +		ret = regmap_read(chip->regmap, INA2XX_POWER, &val);
> > +		if (ret < 0)
> > +			return ret;
> >  	}
> >  
> >  	time_b = iio_get_time_ns(indio_dev);  
> 
> --
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