RE: [PATCH 15/16] iio: adc: max1027: Support software triggers

[Sa, Nuno]

> -----Original Message-----
> From: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
> Sent: Thursday, September 2, 2021 2:25 PM
> To: Sa, Nuno <Nuno.Sa@xxxxxxxxxx>
> Cc: Jonathan Cameron <jic23@xxxxxxxxxx>; Lars-Peter Clausen
> <lars@xxxxxxxxxx>; Thomas Petazzoni
> <thomas.petazzoni@xxxxxxxxxxx>; linux-iio@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH 15/16] iio: adc: max1027: Support software
> triggers
> 
> [External]
> 
> Hi Nuno,
> 
> "Sa, Nuno" <Nuno.Sa@xxxxxxxxxx> wrote on Fri, 20 Aug 2021 07:58:25
> +0000:
> 
> > > -----Original Message-----
> > > From: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
> > > Sent: Wednesday, August 18, 2021 1:12 PM
> > > To: Jonathan Cameron <jic23@xxxxxxxxxx>; Lars-Peter Clausen
> > > <lars@xxxxxxxxxx>
> > > Cc: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxx>; linux-
> > > iio@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Miquel Raynal
> > > <miquel.raynal@xxxxxxxxxxx>
> > > Subject: [PATCH 15/16] iio: adc: max1027: Support software triggers
> > >
> > > [External]
> > >
> > > Now that max1027_trigger_handler() has been freed from
> handling
> > > hardware
> > > triggers EOC situations, we can use it for what it has been designed
> in
> > > the first place: trigger software originated conversions. In other
> > > words, when userspace initiates a conversion with a sysfs trigger or
> a
> > > hrtimer trigger, we must do all configuration steps, ie:
> > > 1- Configuring the trigger
> > > 2- Configuring the channels to scan
> > > 3- Starting the conversion (actually done automatically by step 2 in
> > >    this case)
> > > 4- Waiting for the conversion to end
> > > 5- Retrieving the data from the ADC
> > > 6- Push the data to the IIO core and notify it
> > >
> > > Add the missing steps to this helper and drop the trigger
> verification
> > > hook otherwise software triggers would simply not be accepted at
> all.
> > >
> > > Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
> > > ---
> > >  drivers/iio/adc/max1027.c | 26 ++++++++++++++------------
> > >  1 file changed, 14 insertions(+), 12 deletions(-)
> > >
> > > diff --git a/drivers/iio/adc/max1027.c b/drivers/iio/adc/max1027.c
> > > index 8c5995ae59f2..bb437e43adaf 100644
> > > --- a/drivers/iio/adc/max1027.c
> > > +++ b/drivers/iio/adc/max1027.c
> > > @@ -413,17 +413,6 @@ static int
> max1027_debugfs_reg_access(struct
> > > iio_dev *indio_dev,
> > >  	return spi_write(st->spi, val, 1);
> > >  }
> > >
> > > -static int max1027_validate_trigger(struct iio_dev *indio_dev,
> > > -				    struct iio_trigger *trig)
> > > -{
> > > -	struct max1027_state *st = iio_priv(indio_dev);
> > > -
> > > -	if (st->trig != trig)
> > > -		return -EINVAL;
> > > -
> > > -	return 0;
> > > -}
> > > -
> > >  static int max1027_set_cnvst_trigger_state(struct iio_trigger *trig,
> > > bool state)
> > >  {
> > >  	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
> > > @@ -512,7 +501,21 @@ static irqreturn_t
> max1027_trigger_handler(int
> > > irq, void *private)
> > >
> > >  	pr_debug("%s(irq=%d, private=0x%p)\n", __func__, irq,
> > > private);
> > >
> > > +	ret = max1027_configure_trigger(indio_dev);
> > > +	if (ret)
> > > +		goto out;
> > > +
> > > +	ret = max1027_configure_chans_to_scan(indio_dev);
> > > +	if (ret)
> > > +		goto out;
> > > +
> > > +	ret = max1027_wait_eoc(indio_dev);
> > > +	if (ret)
> > > +		goto out;
> > > +
> > >  	ret = max1027_read_scan(indio_dev);
> >
> > There's something that I'm not getting... How are we checking that
> > we have software triggers? This API is called only if the device
> > allocates it's own trigger which will happen if there's a spi IRQ.
> >
> > I'm probably missing something as this series is fairly big but the way
> > I would do it is (in the probe):
> >
> > - always call 'devm_iio_triggered_buffer_setup()' function and
> properly use
> > buffer ops [1] (for example, you can use 'validate_scan_mask()' to
> setup the
> > channels to read);
> > - only allocate a trigger if an IRQ is present in which case, we assume
> HW
> > triggering is supported.
> 
> I think these are the exact steps that are enforced in the next patch,
> I can squash them if you wish but I think it makes sense to have it in
> two steps.
> 

Yeah, my bad here...

- Nuno Sá