Message-ID: <b9ab676489de3575984dac5610fcf05fd8742a38.camel@analog.com>
Date:   Thu, 30 Apr 2020 08:10:29 +0000
From:   "Ardelean, Alexandru" <alexandru.Ardelean@...log.com>
To:     "Eugen.Hristev@...rochip.com" <Eugen.Hristev@...rochip.com>,
        "jic23@...nel.org" <jic23@...nel.org>
CC:     "Ludovic.Desroches@...rochip.com" <Ludovic.Desroches@...rochip.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] iio: at91-sama5d2_adc: split
 at91_adc_current_chan_is_touch() helper

On Thu, 2020-04-30 at 07:30 +0000, Ardelean, Alexandru wrote:
> On Mon, 2020-04-27 at 13:00 +0000, Ardelean, Alexandru wrote:
> > [External]
> > 
> > On Mon, 2020-04-27 at 12:20 +0000, Eugen.Hristev@...rochip.com wrote:
> > > [External]
> > > 
> > > On 15.04.2020 09:33, Ardelean, Alexandru wrote:
> > > 
> > > > On Tue, 2020-04-14 at 18:45 +0100, Jonathan Cameron wrote:
> > > > > On Tue, 14 Apr 2020 12:22:45 +0000
> > > > > <Eugen.Hristev@...rochip.com> wrote:
> > > > > 
> > > > > > On 13.04.2020 20:05, Jonathan Cameron wrote:
> > > > > > > On Wed, 4 Mar 2020 10:42:18 +0200
> > > > > > > Alexandru Ardelean <alexandru.ardelean@...log.com> wrote:
> > > > > > > 
> > > > > > > > This change moves the logic to check if the current channel is
> > > > > > > > the
> > > > > > > > touchscreen channel to a separate helper.
> > > > > > > > This reduces some code duplication, but the main intent is to
> > > > > > > > re-
> > > > > > > > use
> > > > > > > > this
> > > > > > > > in the next patches.
> > > > > > > > 
> > > > > > > > Signed-off-by: Alexandru Ardelean <alexandru.ardelean@...log.com
> > > > > > > > >
> > > > > > > Eugen / Ludovic,
> > > > > > > 
> > > > > > > Have you had a chance to look at this series?
> > > > > > 
> > > > > > Hi Jonathan,
> > > > > > 
> > > > > > Does the patch apply correctly for you ?
> > > > > 
> > > > > I haven't tried yet :)
> > > > > 
> > > > 
> > > > I've rebased this patchset on top of current iio/testing and it still
> > > > applies.
> > > > 
> > > 
> > > Hi Alex,
> > > 
> > > I tried this patch on top of my tree (however I am testing with an older 
> > > kernel 5.4) , and I have issues starting the buffer after you moved my 
> > > code to the preenable callback.
> > > 
> > > Namely, on the line:
> > > 
> > > if (!(indio_dev->currentmode & INDIO_ALL_TRIGGERED_MODES))
> > >                 return -EINVAL;
> 
> In the meantime I found this patch:
> https://urldefense.com/v3/__https://lore.kernel.org/linux-iio/1431525891-19285-5-git-send-email-lars@metafoo.de/__;!!A3Ni8CS0y2Y!ocQuNvFF_8rd-cCvMNXU0cTk9mLezpCPyzelQyhbxMGdKgFo0_JTgTD1q1VU-kj10aqxxA$ 
> 
> from about ~5 years ago;
> 
> if this patch is a valid proposal, it could fix this case as well;
> well, it might break others, so applying it [now] would need some general
> review
> of all pre/post enable/disable hooks
> 

So, apologies if this will start to seem like spamming.
I decided to do a bit of shell magic for this:

get_files() {
git grep -w iio_buffer_setup_ops  | grep drivers | cut -d: -f1 | sort | uniq
}

for file in $(get_files) ; do
    if grep -q currentmode $file ; then
        echo $file
    fi
done

It finds 4 drivers.
Though, `get_files()` will return 56 files.

drivers/iio/accel/bmc150-accel-core.c
drivers/iio/adc/at91-sama5d2_adc.c
drivers/iio/adc/stm32-dfsdm-adc.c
drivers/iio/magnetometer/rm3100-core.c

The rm3100 driver doesn't do any checks in the setup_ops for 'currentmode' as
far as I could see.

So, Lars' patch could work nicely to fix this current case and not break others.

Semantically though, it would sound nicer to have a 'nextmode' parameter
somewhere; maybe on the setup_ops(indio_dev, nextmode)?
Though, only those 3 drivers would really ever use it; so doing it like that
sounds like overkill.

So, we're left with Lars' patch or we could add an 'indio_dev->nextmode' field,
that may be used in just these 3 drivers [which again: sounds overkill at this
point in time].

Alternatively, this 'indio_dev->currentmode' could be removed from all these 3
drivers somehow. But that needs testing and a thorough understanding of all 3
drivers and what they're doing, to do properly.

@Jonathan: what do you think?

In any case, pending a reply, I'll send Lars' patch.
Even if we come to a different conclusion we have something to start with.
But, if the conclusion is that Lars' patch is a good solution now, it can be
applied.


> > Apologies for the breakage.
> > 
> > For the touch-part I don't see that code being executed.
> > 
> > But a question is: does the driver need to check for the currentmode?
> > Or is that something that the IIO core should do?
> > 
> > > And with this , the preenable fails on my side, because the current mode 
> > > is not yet switched to triggered.
> > > 
> > > I do remember adding this line with a specific reason. It may be related 
> > > to touchscreen operations, but I have to retest the touch with and 
> > > without this line and your patch.
> > > 
> > > Meanwhile, maybe you have any suggestions on how to fix the buffer ? 
> > 
> > Well, there was the question of whether iio_triggered_buffer_postenable()
> > [to
> > attach the pollfunc] makes sense to be called first/last in the old
> > at91_adc_buffer_postenable(), and the answer was 'last'; so then one
> > solution
> > was to move things to preenable().
> > 
> > Going back to the old patch isn't ideal, as the idea was to make the
> > position
> > of
> > iio_triggered_buffer_postenable() consistent across all drivers, so that it
> > can
> > be removed [and moved to the IIO core].
> > 
> > But if we need revert the patch, then I guess it's fine.
> > The only solution I see right now [for going forward], is to remove that
> > check
> > for 'currrentmode'
> > 
> > > This check here makes any sense to you ?
> > 
> > I think Jonathan may have to add some input here, but I think that in this
> > current situation, checking 'currentmode' looks like is re-validating how
> > the
> > device was configured via the IIO framework.
> > I am not sure if it's needed or not.
> > 
> > > Thanks,
> > > Eugen
> > > 
> > > > > > I will try to test it , if I manage to apply it.
> > > > > > I can only test the ADC though because at this moment I do not have
> > > > > > a
> > > > > > touchscreen at disposal.
> > > > > > 
> > > > > > Meanwhile, the code looks good for me,
> > > > > > 
> > > > > > Reviewed-by: Eugen Hristev <eugen.hristev@...rochip.com>
> > > > > > 
> > > > > > By the way, I do not know if my two pending patches on this driver
> > > > > > will
> > > > > > conflict or not.
> > > > > 
> > > > > As this is a long term rework patch at heart, there isn't any
> > > > > particular
> > > > > rush as long as we don't loose it forever!
> > > > > 
> > > > > Thanks,
> > > > > 
> > > > > Jonathan
> > > > > 
> > > > > > Eugen
> > > > > > 
> > > > > > > Thanks,
> > > > > > > 
> > > > > > > Jonathan
> > > > > > > 
> > > > > > > > ---
> > > > > > > > 
> > > > > > > > This patchset continues discussion:
> > > > > > > > 
> > > > > > > > https://urldefense.com/v3/__https://lore.kernel.org/linux-iio/20191023082508.17583-1-alexandru.ardelean@analog.com/__;!!A3Ni8CS0y2Y!ql1bYiNMPFlz1twnCCAQpiEBvpzxR_VHAPL712rWFfwy2TSKjZ2UhGBoV7-29Syny6z0yg$
> > > > > > > > 
> > > > > > > > Apologies for the delay.
> > > > > > > > 
> > > > > > > > Changelog v1 -> v2:
> > > > > > > > * added patch 'iio: at91-sama5d2_adc: split
> > > > > > > > at91_adc_current_chan_is_touch()
> > > > > > > >     helper'
> > > > > > > > * renamed at91_adc_buffer_postenable() ->
> > > > > > > > at91_adc_buffer_preenable()
> > > > > > > >     - at91_adc_buffer_postenable() - now just calls
> > > > > > > >       iio_triggered_buffer_postenable() if the channel isn't the
> > > > > > > > touchscreen
> > > > > > > >       channel
> > > > > > > > * renamed at91_adc_buffer_predisable() ->
> > > > > > > > at91_adc_buffer_postdisable()
> > > > > > > >     - at91_adc_buffer_predisable() - now just calls
> > > > > > > >       iio_triggered_buffer_predisable() if the channel isn't the
> > > > > > > > touchscreen
> > > > > > > >       channel
> > > > > > > > 
> > > > > > > >    drivers/iio/adc/at91-sama5d2_adc.c | 31 +++++++++++++++----
> > > > > > > > ----
> > > > > > > > -------
> > > > > > > >    1 file changed, 15 insertions(+), 16 deletions(-)
> > > > > > > > 
> > > > > > > > diff --git a/drivers/iio/adc/at91-sama5d2_adc.c
> > > > > > > > b/drivers/iio/adc/at91-
> > > > > > > > sama5d2_adc.c
> > > > > > > > index a5c7771227d5..f2a74c47c768 100644
> > > > > > > > --- a/drivers/iio/adc/at91-sama5d2_adc.c
> > > > > > > > +++ b/drivers/iio/adc/at91-sama5d2_adc.c
> > > > > > > > @@ -873,18 +873,24 @@ static int at91_adc_dma_start(struct
> > > > > > > > iio_dev
> > > > > > > > *indio_dev)
> > > > > > > >         return 0;
> > > > > > > >    }
> > > > > > > > 
> > > > > > > > +static bool at91_adc_current_chan_is_touch(struct iio_dev
> > > > > > > > *indio_dev)
> > > > > > > > +{
> > > > > > > > +     struct at91_adc_state *st = iio_priv(indio_dev);
> > > > > > > > +
> > > > > > > > +     return !!bitmap_subset(indio_dev->active_scan_mask,
> > > > > > > > +                            &st->touch_st.channels_bitmask,
> > > > > > > > +                            AT91_SAMA5D2_MAX_CHAN_IDX + 1);
> > > > > > > > +}
> > > > > > > > +
> > > > > > > >    static int at91_adc_buffer_postenable(struct iio_dev
> > > > > > > > *indio_dev)
> > > > > > > >    {
> > > > > > > >         int ret;
> > > > > > > >         struct at91_adc_state *st = iio_priv(indio_dev);
> > > > > > > > 
> > > > > > > >         /* check if we are enabling triggered buffer or the
> > > > > > > > touchscreen
> > > > > > > > */
> > > > > > > > -     if (bitmap_subset(indio_dev->active_scan_mask,
> > > > > > > > -                       &st->touch_st.channels_bitmask,
> > > > > > > > -                       AT91_SAMA5D2_MAX_CHAN_IDX + 1)) {
> > > > > > > > -             /* touchscreen enabling */
> > > > > > > > +     if (at91_adc_current_chan_is_touch(indio_dev))
> > > > > > > >                 return at91_adc_configure_touch(st, true);
> > > > > > > > -     }
> > > > > > > > +
> > > > > > > >         /* if we are not in triggered mode, we cannot enable the
> > > > > > > > buffer.
> > > > > > > > */
> > > > > > > >         if (!(indio_dev->currentmode &
> > > > > > > > INDIO_ALL_TRIGGERED_MODES))
> > > > > > > >                 return -EINVAL;
> > > > > > > > @@ -906,12 +912,9 @@ static int
> > > > > > > > at91_adc_buffer_predisable(struct
> > > > > > > > iio_dev *indio_dev)
> > > > > > > >         u8 bit;
> > > > > > > > 
> > > > > > > >         /* check if we are disabling triggered buffer or the
> > > > > > > > touchscreen
> > > > > > > > */
> > > > > > > > -     if (bitmap_subset(indio_dev->active_scan_mask,
> > > > > > > > -                       &st->touch_st.channels_bitmask,
> > > > > > > > -                       AT91_SAMA5D2_MAX_CHAN_IDX + 1)) {
> > > > > > > > -             /* touchscreen disable */
> > > > > > > > +     if (at91_adc_current_chan_is_touch(indio_dev))
> > > > > > > >                 return at91_adc_configure_touch(st, false);
> > > > > > > > -     }
> > > > > > > > +
> > > > > > > >         /* if we are not in triggered mode, nothing to do here
> > > > > > > > */
> > > > > > > >         if (!(indio_dev->currentmode &
> > > > > > > > INDIO_ALL_TRIGGERED_MODES))
> > > > > > > >                 return -EINVAL;
> > > > > > > > @@ -1886,14 +1889,10 @@ static __maybe_unused int
> > > > > > > > at91_adc_resume(struct
> > > > > > > > device *dev)
> > > > > > > >                 return 0;
> > > > > > > > 
> > > > > > > >         /* check if we are enabling triggered buffer or the
> > > > > > > > touchscreen
> > > > > > > > */
> > > > > > > > -     if (bitmap_subset(indio_dev->active_scan_mask,
> > > > > > > > -                       &st->touch_st.channels_bitmask,
> > > > > > > > -                       AT91_SAMA5D2_MAX_CHAN_IDX + 1)) {
> > > > > > > > -             /* touchscreen enabling */
> > > > > > > > +     if (at91_adc_current_chan_is_touch(indio_dev))
> > > > > > > >                 return at91_adc_configure_touch(st, true);
> > > > > > > > -     } else {
> > > > > > > > +     else
> > > > > > > >                 return at91_adc_configure_trigger(st->trig,
> > > > > > > > true);
> > > > > > > > -     }
> > > > > > > > 
> > > > > > > >         /* not needed but more explicit */
> > > > > > > >         return 0;

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