Re: [PATCH v2 26/46] mfd: ti_am335x_tscadc: Use FIELD_PREP() when relevant in the header

[Jonathan Cameron <jic23@kernel.org>]

On Wed, 15 Sep 2021 09:48:47 +0200
Miquel Raynal <miquel.raynal@bootlin.com> wrote:

> Hi Jonathan,
> 
> jic23@kernel.org wrote on Sun, 5 Sep 2021 14:13:32 +0100:
> 
> > On Thu,  2 Sep 2021 23:51:24 +0200
> > Miquel Raynal <miquel.raynal@bootlin.com> wrote:
> >   
> > > Use the FIELD_PREP() macro when relevant. Sometimes reorder the lines to
> > > be able to use the relevant bitmask.
> > > 
> > > Mind the s/%d/%ld/ change in a log due to the type change following the
> > > use of FIELD_PREP() in the header.
> > > 
> > > Suggested-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> > > Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>    
> > What you have here is fine, but I would take it a step further and push the
> > FIELD_PREP() calls directly inline in the code.  There is little advantage
> > beyond saving a few characters in
> > 
> > STEPENB(3)
> > 
> > rather than
> > 
> > FIELD_PREP(STEPENB_MASK, 3)
> > 
> > If you don't want to go that far this is still an improvement so
> > Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> >   
> > > ---
> > >  drivers/iio/adc/ti_am335x_adc.c      |  2 +-
> > >  include/linux/mfd/ti_am335x_tscadc.h | 31 ++++++++++++++--------------
> > >  2 files changed, 17 insertions(+), 16 deletions(-)
> > > 
> > > diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c
> > > index e946903b0993..54c410b6ca07 100644
> > > --- a/drivers/iio/adc/ti_am335x_adc.c
> > > +++ b/drivers/iio/adc/ti_am335x_adc.c
> > > @@ -126,7 +126,7 @@ static void tiadc_step_config(struct iio_dev *indio_dev)
> > >  		chan = adc_dev->channel_line[i];
> > >  
> > >  		if (adc_dev->step_avg[i] > STEPCONFIG_AVG_16) {
> > > -			dev_warn(dev, "chan %d step_avg truncating to %d\n",
> > > +			dev_warn(dev, "chan %d step_avg truncating to %ld\n",
> > >  				 chan, STEPCONFIG_AVG_16);
> > >  			adc_dev->step_avg[i] = STEPCONFIG_AVG_16;
> > >  		}
> > > diff --git a/include/linux/mfd/ti_am335x_tscadc.h b/include/linux/mfd/ti_am335x_tscadc.h
> > > index 4de16fc3d74f..29095c0dc6d8 100644
> > > --- a/include/linux/mfd/ti_am335x_tscadc.h
> > > +++ b/include/linux/mfd/ti_am335x_tscadc.h
> > > @@ -8,6 +8,7 @@
> > >  #ifndef __LINUX_TI_AM335X_TSCADC_MFD_H
> > >  #define __LINUX_TI_AM335X_TSCADC_MFD_H
> > >  
> > > +#include <linux/bitfield.h>
> > >  #include <linux/mfd/core.h>
> > >  
> > >  #define REG_RAWIRQSTATUS	0x024
> > > @@ -40,7 +41,7 @@
> > >  
> > >  /* Step Enable */
> > >  #define STEPENB_MASK		GENMASK(16, 0)
> > > -#define STEPENB(val)		((val) << 0)
> > > +#define STEPENB(val)		FIELD_PREP(STEPENB_MASK, (val))    
> > 
> > My inclination with these is to drop the macro entirely and
> > just use FIELD_PREP(STEPENB_MASK, xxx) inline directly.
> > There is no loss of clarity in doing so and it gets you to a state
> > where you only have one macro per field which is nice for checking
> > purposes.  
> 
> Actually I don't like too much leaking FIELD_PREP()s directly in the
> code because (and this is really a personal feeling) I found them
> rather less straightforward to understand than a good old BIT() for
> example. Moreover, I've already hacked in a lot of different
> places and moving these definitions in the code directly would
> produce a big diff, overall hardening possible future git-blames.
> 
> However, I rather agree on the fact that there is no point in defining
> a mask and then using that mask in another macro unless that mask is
> reused somewhere else. So if it's fine for you, I'll provide a new
> version with a reduced number of defines in this file. Would this work
> for you?

That will be fine.

Thanks,

Jonathan

>  
> >   
> > >  #define ENB(val)		BIT(val)
> > >  #define STPENB_STEPENB		STEPENB(GENMASK(16, 0))
> > >  #define STPENB_STEPENB_TC	STEPENB(GENMASK(12, 0))
> > > @@ -58,11 +59,11 @@
> > >  
> > >  /* Step Configuration */
> > >  #define STEPCONFIG_MODE_MASK	GENMASK(1, 0)
> > > -#define STEPCONFIG_MODE(val)	((val) << 0)
> > > +#define STEPCONFIG_MODE(val)	FIELD_PREP(STEPCONFIG_MODE_MASK, (val))
> > >  #define STEPCONFIG_MODE_SWCNT	STEPCONFIG_MODE(1)
> > >  #define STEPCONFIG_MODE_HWSYNC	STEPCONFIG_MODE(2)
> > >  #define STEPCONFIG_AVG_MASK	GENMASK(4, 2)
> > > -#define STEPCONFIG_AVG(val)	((val) << 2)
> > > +#define STEPCONFIG_AVG(val)	FIELD_PREP(STEPCONFIG_AVG_MASK, (val))
> > >  #define STEPCONFIG_AVG_16	STEPCONFIG_AVG(4)
> > >  #define STEPCONFIG_XPP		BIT(5)
> > >  #define STEPCONFIG_XNN		BIT(6)
> > > @@ -70,43 +71,43 @@
> > >  #define STEPCONFIG_YNN		BIT(8)
> > >  #define STEPCONFIG_XNP		BIT(9)
> > >  #define STEPCONFIG_YPN		BIT(10)
> > > -#define STEPCONFIG_RFP(val)	((val) << 12)
> > >  #define STEPCONFIG_RFP_VREFP	GENMASK(13, 12)
> > > +#define STEPCONFIG_RFP(val)	FIELD_PREP(STEPCONFIG_RFP_VREFP, (val))
> > >  #define STEPCONFIG_INM_MASK	GENMASK(18, 15)
> > > -#define STEPCONFIG_INM(val)	((val) << 15)
> > > +#define STEPCONFIG_INM(val)	FIELD_PREP(STEPCONFIG_INM_MASK, (val))
> > >  #define STEPCONFIG_INM_ADCREFM	STEPCONFIG_INM(8)
> > >  #define STEPCONFIG_INP_MASK	GENMASK(22, 19)
> > > -#define STEPCONFIG_INP(val)	((val) << 19)
> > > +#define STEPCONFIG_INP(val)	FIELD_PREP(STEPCONFIG_INP_MASK, (val))
> > >  #define STEPCONFIG_INP_AN4	STEPCONFIG_INP(4)
> > >  #define STEPCONFIG_INP_ADCREFM	STEPCONFIG_INP(8)
> > >  #define STEPCONFIG_FIFO1	BIT(26)
> > > -#define STEPCONFIG_RFM(val)	((val) << 23)
> > >  #define STEPCONFIG_RFM_VREFN	GENMASK(24, 23)
> > > +#define STEPCONFIG_RFM(val)	FIELD_PREP(STEPCONFIG_RFM_VREFN, (val))
> > >  
> > >  /* Delay register */
> > >  #define STEPDELAY_OPEN_MASK	GENMASK(17, 0)
> > > -#define STEPDELAY_OPEN(val)	((val) << 0)
> > > +#define STEPDELAY_OPEN(val)	FIELD_PREP(STEPDELAY_OPEN_MASK, (val))
> > >  #define STEPCONFIG_OPENDLY	STEPDELAY_OPEN(0x098)
> > >  #define STEPDELAY_SAMPLE_MASK	GENMASK(31, 24)
> > > -#define STEPDELAY_SAMPLE(val)	((val) << 24)
> > > +#define STEPDELAY_SAMPLE(val)	FIELD_PREP(STEPDELAY_SAMPLE_MASK, (val))
> > >  #define STEPCONFIG_SAMPLEDLY	STEPDELAY_SAMPLE(0)
> > >  
> > >  /* Charge Config */
> > >  #define STEPCHARGE_RFP_MASK	GENMASK(14, 12)
> > > -#define STEPCHARGE_RFP(val)	((val) << 12)
> > > +#define STEPCHARGE_RFP(val)	FIELD_PREP(STEPCHARGE_RFP_MASK, (val))
> > >  #define STEPCHARGE_RFP_XPUL	STEPCHARGE_RFP(1)
> > >  #define STEPCHARGE_INM_MASK	GENMASK(18, 15)
> > > -#define STEPCHARGE_INM(val)	((val) << 15)
> > > +#define STEPCHARGE_INM(val)	FIELD_PREP(STEPCHARGE_INM_MASK, (val))
> > >  #define STEPCHARGE_INM_AN1	STEPCHARGE_INM(1)
> > >  #define STEPCHARGE_INP_MASK	GENMASK(22, 19)
> > > -#define STEPCHARGE_INP(val)	((val) << 19)
> > > +#define STEPCHARGE_INP(val)	FIELD_PREP(STEPCHARGE_INP_MASK, (val))
> > >  #define STEPCHARGE_RFM_MASK	GENMASK(24, 23)
> > > -#define STEPCHARGE_RFM(val)	((val) << 23)
> > > +#define STEPCHARGE_RFM(val)	FIELD_PREP(STEPCHARGE_RFM_MASK, (val))
> > >  #define STEPCHARGE_RFM_XNUR	STEPCHARGE_RFM(1)
> > >  
> > >  /* Charge delay */
> > >  #define CHARGEDLY_OPEN_MASK	GENMASK(17, 0)
> > > -#define CHARGEDLY_OPEN(val)	((val) << 0)
> > > +#define CHARGEDLY_OPEN(val)	FIELD_PREP(CHARGEDLY_OPEN_MASK, (val))
> > >  #define CHARGEDLY_OPENDLY	CHARGEDLY_OPEN(0x400)
> > >  
> > >  /* Control register */
> > > @@ -115,7 +116,7 @@
> > >  #define CNTRLREG_STEPCONFIGWRT	BIT(2)
> > >  #define CNTRLREG_POWERDOWN	BIT(4)
> > >  #define CNTRLREG_AFE_CTRL_MASK	GENMASK(6, 5)
> > > -#define CNTRLREG_AFE_CTRL(val)	((val) << 5)
> > > +#define CNTRLREG_AFE_CTRL(val)	FIELD_PREP(CNTRLREG_AFE_CTRL_MASK, (val))
> > >  #define CNTRLREG_4WIRE		CNTRLREG_AFE_CTRL(1)
> > >  #define CNTRLREG_5WIRE		CNTRLREG_AFE_CTRL(2)
> > >  #define CNTRLREG_8WIRE		CNTRLREG_AFE_CTRL(3)    
> >   
> 
> Thanks,
> Miquèl