linux-kernel - Re: [PATCH v2] iio/axp288_adc: add missing channel info mask

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Date:	Fri, 10 Apr 2015 02:58:22 -0700
From:	Jacob Pan <jacob.jun.pan@...ux.intel.com>
To:	Jonathan Cameron <jic23@...nel.org>
Cc:	IIO <linux-iio@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Lee Jones <lee.jones@...aro.org>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Hartmut Knaack <knaack.h@....de>,
	Aaron Lu <aaron.lu@...el.com>,
	Todd Brandt <todd.e.brandt@...ux.intel.com>
Subject: Re: [PATCH v2] iio/axp288_adc: add missing channel info mask

On Thu, 09 Apr 2015 18:52:12 +0100
Jonathan Cameron <jic23@...nel.org> wrote:

> On 09/04/15 18:50, Jonathan Cameron wrote:
> > On 09/04/15 18:02, Jacob Pan wrote:
> >> On Thu, 09 Apr 2015 14:18:49 +0100
> >> Jonathan Cameron <jic23@...nel.org> wrote:
> >>
> >>> On 06/04/15 19:38, Jacob Pan wrote:
> >>>> Commit 65de7654d39c70c2b ("iio: iio: Fix iio_channel_read return
> >>>> if channel havn't info") added a check for valid info masks.
> >>>>
> >>>> This patch adds missing channel info masks for all ADC channels.
> >>>> Otherwise, iio_read_channel_raw() would return -EINVAL when
> >>>> called by consumer drivers.
> >>>>
> >>>> Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> >>>
> >>> This makes me a little nervous. Why did we have the separate raw
> >>> and processed paths in the read_raw function in the first place?
> >>>
> >> Good point, I failed to explain that the reason to have separate
> >> raw and processed was that the raw channels happened to need some
> >> special processing in axp288_adc_set_ts(), since I have added a
> >> check for address:
> >> 	/* channels other than GPADC do not need to switch TS pin
> >> */ if (address != AXP288_GP_ADC_H)
> >> 		return 0;
> >>
> >> we no longer need special case the channels based on RAW flag.
> >> Thinking back it was kind of an abuse.
> >>
> >>> Also this changes the exposed userspace ABI by dropping those
> >>> processed attributes that already exist..
> >>>
> >> I don't know the current users outside what we develop internally.
> >> What is your suggestion?
> > Lets go for it on the basis of it is 'fixing' your abuse of the
> > ABI ;) Then any users should long ago have complained about it
> > anyway (did I say that?) We'll take the age old approach. If no one
> > notices we broke the ABI then it's fine.
> > 
> > Have applied to the fixes-togreg branch of iio.git with the
> > description updated to indicate it also fixes the ABI abuse ;)
> > 
> > Anyhow, won't go now until after the merge window anyway I'm afraid.
> > Marked for stable as well.
> > 
> Forgot to say. If it causes any breakage, we simply put back the
> incorrect processed version as well.  That might then cause breakage
> for any in kernel consumers however as they will use that in
> preference to the raw version IIRC.
> > Thanks,
> > 
Good to know. Thanks a lot.
Perhaps I missed it in the kernel, I wish there were more
comments/documentation on the enum to explain its use case for hw
provided data format, and implication for sysfs abi etc.

enum iio_chan_info_enum {
	IIO_CHAN_INFO_RAW = 0,
	IIO_CHAN_INFO_PROCESSED,
...


}
> > Jonathan
> >>
> >>> Jonathan
> >>>> ---
> >>>>  drivers/iio/adc/axp288_adc.c | 12 ++++++------
> >>>>  1 file changed, 6 insertions(+), 6 deletions(-)
> >>>>
> >>>> diff --git a/drivers/iio/adc/axp288_adc.c
> >>>> b/drivers/iio/adc/axp288_adc.c index 08bcfb0..56008a8 100644
> >>>> --- a/drivers/iio/adc/axp288_adc.c
> >>>> +++ b/drivers/iio/adc/axp288_adc.c
> >>>> @@ -53,39 +53,42 @@ static const struct iio_chan_spec const
> >>>> axp288_adc_channels[] = { .channel = 0,
> >>>>  		.address = AXP288_TS_ADC_H,
> >>>>  		.datasheet_name = "TS_PIN",
> >>>> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> >>>>  	}, {
> >>>>  		.indexed = 1,
> >>>>  		.type = IIO_TEMP,
> >>>>  		.channel = 1,
> >>>>  		.address = AXP288_PMIC_ADC_H,
> >>>>  		.datasheet_name = "PMIC_TEMP",
> >>>> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> >>>>  	}, {
> >>>>  		.indexed = 1,
> >>>>  		.type = IIO_TEMP,
> >>>>  		.channel = 2,
> >>>>  		.address = AXP288_GP_ADC_H,
> >>>>  		.datasheet_name = "GPADC",
> >>>> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> >>>>  	}, {
> >>>>  		.indexed = 1,
> >>>>  		.type = IIO_CURRENT,
> >>>>  		.channel = 3,
> >>>>  		.address = AXP20X_BATT_CHRG_I_H,
> >>>>  		.datasheet_name = "BATT_CHG_I",
> >>>> -		.info_mask_separate =
> >>>> BIT(IIO_CHAN_INFO_PROCESSED),
> >>>> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> >>>>  	}, {
> >>>>  		.indexed = 1,
> >>>>  		.type = IIO_CURRENT,
> >>>>  		.channel = 4,
> >>>>  		.address = AXP20X_BATT_DISCHRG_I_H,
> >>>>  		.datasheet_name = "BATT_DISCHRG_I",
> >>>> -		.info_mask_separate =
> >>>> BIT(IIO_CHAN_INFO_PROCESSED),
> >>>> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> >>>>  	}, {
> >>>>  		.indexed = 1,
> >>>>  		.type = IIO_VOLTAGE,
> >>>>  		.channel = 5,
> >>>>  		.address = AXP20X_BATT_V_H,
> >>>>  		.datasheet_name = "BATT_V",
> >>>> -		.info_mask_separate =
> >>>> BIT(IIO_CHAN_INFO_PROCESSED),
> >>>> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> >>>>  	},
> >>>>  };
> >>>>  
> >>>> @@ -151,9 +154,6 @@ static int axp288_adc_read_raw(struct iio_dev
> >>>> *indio_dev, chan->address))
> >>>>  			dev_err(&indio_dev->dev, "TS pin
> >>>> restore\n"); break;
> >>>> -	case IIO_CHAN_INFO_PROCESSED:
> >>>> -		ret = axp288_adc_read_channel(val,
> >>>> chan->address, info->regmap);
> >>>> -		break;
> >>>>  	default:
> >>>>  		ret = -EINVAL;
> >>>>  	}
> >>>>
> >>>
> >>
> >> [Jacob Pan]
> >> --
> >> To unsubscribe from this list: send the line "unsubscribe
> >> linux-iio" in the body of a message to majordomo@...r.kernel.org
> >> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >>
> > 
> > --
> > To unsubscribe from this list: send the line "unsubscribe
> > linux-iio" in the body of a message to majordomo@...r.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > 
> 




-- 
Jacob Pan
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