Message-ID: <be31bfcde7dc35b07855302d5cbf6db42bc7f634.camel@analog.com>
Date:   Thu, 30 Apr 2020 07:30:23 +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 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://lore.kernel.org/linux-iio/1431525891-19285-5-git-send-email-lars@metafoo.de/

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

> 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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