Re: [PATCH 1/2] iio: adc: ti-ads1015: write config register only on change

[Jonathan Cameron <jic23@jic23.retrosnub.co.uk>]

On Sun, 3 Sep 2017 16:56:35 +0100
Jonathan Cameron <jic23@kernel.org> wrote:

> On Thu, 24 Aug 2017 10:25:51 +0200
> Ladislav Michl <ladis@linux-mips.org> wrote:
> 
> > There is no point writing ADS1015_CFG_REG when configuration
> > didn't change. Avoid that.
> > 
> > Cc: Daniel Baluta <daniel.baluta@gmail.com>
> > Cc: Jonathan Cameron <jic23@kernel.org>
> > Cc: Akinobu Mita <akinobu.mita@gmail.com>
> > Signed-off-by: Ladislav Michl <ladis@linux-mips.org>  
> 
> Fair enough.  Applied to the togreg branch of iio.git which will be
> pushed out as testing for the autobuilders to play with it.
> 
> Thanks,
> 
> Jonathan

There was a bit of fuzz so please check the result once it is
up in the testing branch.

Jonathan

> 
> > ---
> >  drivers/iio/adc/ti-ads1015.c | 19 +++++++++----------
> >  1 file changed, 9 insertions(+), 10 deletions(-)
> > 
> > diff --git a/drivers/iio/adc/ti-ads1015.c b/drivers/iio/adc/ti-ads1015.c
> > index 7838e39c790c..034e48566ab5 100644
> > --- a/drivers/iio/adc/ti-ads1015.c
> > +++ b/drivers/iio/adc/ti-ads1015.c
> > @@ -240,7 +240,7 @@ static int ads1015_set_power_state(struct ads1015_data *data, bool on)
> >  static
> >  int ads1015_get_adc_result(struct ads1015_data *data, int chan, int *val)
> >  {
> > -	int ret, pga, dr, conv_time;
> > +	int ret, pga, dr, dr_old, conv_time;
> >  	unsigned int old, mask, cfg;
> >  
> >  	if (chan < 0 || chan >= ADS1015_CHANNELS)
> > @@ -256,17 +256,16 @@ int ads1015_get_adc_result(struct ads1015_data *data, int chan, int *val)
> >  		ADS1015_CFG_DR_MASK;
> >  	cfg = chan << ADS1015_CFG_MUX_SHIFT | pga << ADS1015_CFG_PGA_SHIFT |
> >  		dr << ADS1015_CFG_DR_SHIFT;
> > -
> >  	cfg = (old & ~mask) | (cfg & mask);
> >  
> > -	ret = regmap_write(data->regmap, ADS1015_CFG_REG, cfg);
> > -	if (ret)
> > -		return ret;
> > -
> > -	if (old != cfg || data->conv_invalid) {
> > -		int dr_old = (old & ADS1015_CFG_DR_MASK) >>
> > -				ADS1015_CFG_DR_SHIFT;
> > -
> > +	if (old != cfg) {
> > +		ret = regmap_write(data->regmap, ADS1015_CFG_REG, cfg);
> > +		if (ret)
> > +			return ret;
> > +		data->conv_invalid = true;
> > +	}
> > +	if (data->conv_invalid) {
> > +		dr_old = (old & ADS1015_CFG_DR_MASK) >> ADS1015_CFG_DR_SHIFT;
> >  		conv_time = DIV_ROUND_UP(USEC_PER_SEC, data->data_rate[dr_old]);
> >  		conv_time += DIV_ROUND_UP(USEC_PER_SEC, data->data_rate[dr]);
> >  		usleep_range(conv_time, conv_time + 1);  
> 
> --
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