LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Jonathan Cameron <jic23@kernel.org>
To: "hui.liu" <hui.liu@mediatek.com>
Cc: Jonathan Cameron <Jonathan.Cameron@Huawei.com>,
	<robh+dt@kernel.org>, <lars@metafoo.de>, <pmeerw@pmeerw.net>,
	<srv_heupstream@mediatek.com>, <zhiyong.tao@mediatek.com>,
	<chun-hung.wu@mediatek.com>, <yingjoe.chen@mediatek.com>,
	<seiya.wang@mediatek.com>, <matthias.bgg@gmail.com>,
	<s.hauer@pengutronix.de>, <devicetree@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-iio@vger.kernel.org>, <linux-mediatek@lists.infradead.org>
Subject: Re: [PATCH v1 1/2] iio: mtk-auxadc: add support IIO_CHAN_INFO_RAW case
Date: Tue, 17 Aug 2021 16:54:18 +0100	[thread overview]
Message-ID: <20210817165418.4b1cfdce@jic23-huawei> (raw)
In-Reply-To: <470d4a7fbbcbcaa35aa9dcbaab6a2b77f98dc528.camel@mediatek.com>

On Tue, 17 Aug 2021 16:37:52 +0800
hui.liu <hui.liu@mediatek.com> wrote:

> On Sat, 2021-08-14 at 17:10 +0100, Jonathan Cameron wrote:
> > On Fri, 13 Aug 2021 11:46:24 +0800
> > hui.liu <hui.liu@mediatek.com> wrote:
> >   
> > > On Thu, 2021-08-12 at 19:07 +0100, Jonathan Cameron wrote:  
> > > > On Thu, 12 Aug 2021 13:48:43 +0800
> > > > Hui Liu <hui.liu@mediatek.com> wrote:
> > > >     
> > > > > Add support IIO_CHAN_INFO_RAW case.    
> > > > 
> > > > Why?
> > > > 
> > > > We almost never support both RAW and PROCESSED as userspace
> > > > should be
> > > > fine to use either.  There are a few reasons we've let drivers do
> > > > this but I would like know why it matters to you and it
> > > > definitely
> > > > needs to be in the patch description.
> > > >     
> > > 
> > > Hi Jonathan,
> > > 
> > > 1. To support ADC consumers' different types of requirement: some
> > > consumers want to call iio_read_channel_raw to get raw data, the
> > > others
> > > use iio_read_channel_processed to get voltage.  
> > 
> > Give an example of the consumer using the raw channel readback
> > (without
> > acess to any scaling information?)
> >   
> 
> > > 2. In our origin driver, if consumer call
> > > iio_read_channel_processed,
> > > read back value is raw data. 
> > > 
> > > Could we use SCALE instead of PROCESSED in patch for next version,
> > > or
> > > what's your suggestion?  
> > 
> > That would unfortunately be a userspace ABI change.  We can add
> > interfaces
> > but taking them away is normally a problem :( 
> > 
> > Your reasons here are fine, subject to information on what consumer
> > cares
> > about having _RAW, please resend the patch with this information
> > added
> > to the description.
> > 
> > Thanks,
> > 
> > Jonathan  
> 
> 1. We found afe/iio-rescale.c, dac/dpot-dac.c and multiplexer/iio-mux.c 
> call iio_read_channel_raw to get raw data. If they use our ADC driver,
> I think we should support _RAW case. 
> If we support _RAW case, we will add more information in v2
> description.

iio-rescale has recently gained support for processed.
https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git/commit/drivers/iio/afe/iio-rescale.c?h=testing&id=53ebee9499805add3eef630d998c40812e6a1c39
dpot-dac is a rather obscure special case, so I doubt you actually have one of those.
If iio-mux is relevant then we should add processed support to that driver as well.

I would rather see those users of the interface fixed than us
having to tweak lots of drivers to provide _raw when it isn't appropriate for
that piece of hardware.

Jonathan

> 
> 2. Since we change _PROCESSED readback value from raw data to voltage,
> our consumer will make the changes synchronously. 
> 
> > > 
> > > Thanks.
> > >   
> > > > > 
> > > > > Signed-off-by: Hui Liu <hui.liu@mediatek.com>
> > > > > ---
> > > > >  drivers/iio/adc/mt6577_auxadc.c | 16 +++++++++++++++-
> > > > >  1 file changed, 15 insertions(+), 1 deletion(-)
> > > > > 
> > > > > diff --git a/drivers/iio/adc/mt6577_auxadc.c
> > > > > b/drivers/iio/adc/mt6577_auxadc.c
> > > > > index 79c1dd68b909..e995d43287b2 100644
> > > > > --- a/drivers/iio/adc/mt6577_auxadc.c
> > > > > +++ b/drivers/iio/adc/mt6577_auxadc.c
> > > > > @@ -60,7 +60,8 @@ static const struct mtk_auxadc_compatible
> > > > > mt6765_compat = {
> > > > >  		.type = IIO_VOLTAGE,				
> > > > >    
> > > > >  \
> > > > >  		.indexed = 1,					
> > > > >    
> > > > >  \
> > > > >  		.channel = (idx),				
> > > > >     \
> > > > > -		.info_mask_separate =
> > > > > BIT(IIO_CHAN_INFO_PROCESSED), \
> > > > > +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |	
> > > > >    
> > > > >  \
> > > > > +				      BIT(IIO_CHAN_INFO_PROCESS
> > > > > ED), \
> > > > >  }
> > > > >  
> > > > >  static const struct iio_chan_spec mt6577_auxadc_iio_channels[]
> > > > > = {
> > > > > @@ -181,6 +182,19 @@ static int mt6577_auxadc_read_raw(struct
> > > > > iio_dev *indio_dev,
> > > > >  	struct mt6577_auxadc_device *adc_dev =
> > > > > iio_priv(indio_dev);
> > > > >  
> > > > >  	switch (info) {
> > > > > +	case IIO_CHAN_INFO_RAW:
> > > > > +		*val = mt6577_auxadc_read(indio_dev, chan);
> > > > > +		if (*val < 0) {
> > > > > +			dev_notice(indio_dev->dev.parent,
> > > > > +				"failed to sample data on
> > > > > channel[%d]\n",
> > > > > +				chan->channel);
> > > > > +			return *val;
> > > > > +		}
> > > > > +		if (adc_dev->dev_comp->sample_data_cali)
> > > > > +			*val = mt_auxadc_get_cali_data(*val,
> > > > > true);
> > > > > +
> > > > > +		return IIO_VAL_INT;
> > > > > +
> > > > >  	case IIO_CHAN_INFO_PROCESSED:
> > > > >  		*val = mt6577_auxadc_read(indio_dev, chan);
> > > > >  		if (*val < 0) {    
> > > > 
> > > >     
> > 
> >   


  parent reply	other threads:[~2021-08-17 15:56 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-12  5:48 [PATCH v1 0/2] AUXADC: Mediatek auxadc driver Hui Liu
2021-08-12  5:48 ` [PATCH v1 1/2] iio: mtk-auxadc: add support IIO_CHAN_INFO_RAW case Hui Liu
2021-08-12 18:07   ` Jonathan Cameron
     [not found]     ` <042625639032bffe73b60a5c6274511e58e34ef4.camel@mediatek.com>
2021-08-14 16:10       ` Jonathan Cameron
     [not found]         ` <470d4a7fbbcbcaa35aa9dcbaab6a2b77f98dc528.camel@mediatek.com>
2021-08-17 15:54           ` Jonathan Cameron [this message]
2021-08-12  5:48 ` [PATCH v1 2/2] iio: mtk-auxadc: update case IIO_CHAN_INFO_PROCESSED Hui Liu

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210817165418.4b1cfdce@jic23-huawei \
    --to=jic23@kernel.org \
    --cc=Jonathan.Cameron@Huawei.com \
    --cc=chun-hung.wu@mediatek.com \
    --cc=devicetree@vger.kernel.org \
    --cc=hui.liu@mediatek.com \
    --cc=lars@metafoo.de \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-iio@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mediatek@lists.infradead.org \
    --cc=matthias.bgg@gmail.com \
    --cc=pmeerw@pmeerw.net \
    --cc=robh+dt@kernel.org \
    --cc=s.hauer@pengutronix.de \
    --cc=seiya.wang@mediatek.com \
    --cc=srv_heupstream@mediatek.com \
    --cc=yingjoe.chen@mediatek.com \
    --cc=zhiyong.tao@mediatek.com \
    --subject='Re: [PATCH v1 1/2] iio: mtk-auxadc: add support IIO_CHAN_INFO_RAW case' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).