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From: "Sa, Nuno" <Nuno.Sa@analog.com>
To: Jonathan Cameron <jic23@kernel.org>,
	Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
	"linux-iio@vger.kernel.org" <linux-iio@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH 14/16] iio: adc: max1027: Consolidate the end of conversion helper
Date: Mon, 30 Aug 2021 12:44:48 +0000	[thread overview]
Message-ID: <MW4PR03MB6363F50DC6A4B5D682BA16E299CB9@MW4PR03MB6363.namprd03.prod.outlook.com> (raw)
In-Reply-To: <20210830113716.1f7cdc6f@jic23-huawei>



> -----Original Message-----
> From: Jonathan Cameron <jic23@kernel.org>
> Sent: Monday, August 30, 2021 12:37 PM
> To: Miquel Raynal <miquel.raynal@bootlin.com>
> Cc: Lars-Peter Clausen <lars@metafoo.de>; Thomas Petazzoni
> <thomas.petazzoni@bootlin.com>; linux-iio@vger.kernel.org; linux-
> kernel@vger.kernel.org
> Subject: Re: [PATCH 14/16] iio: adc: max1027: Consolidate the end of
> conversion helper
> 
> On Wed, 18 Aug 2021 13:11:37 +0200
> Miquel Raynal <miquel.raynal@bootlin.com> wrote:
> 
> > Now that we have a dedicated handler for End Of Conversion
> interrupts,
> > let's create a second path:
> > - Situation 1: we are using the external hardware trigger, a
> conversion
> >   has been triggered and the ADC pushed the data to its FIFO, we
> need to
> >   retrieve the data and push it to the IIO buffers.
> > - Situation 2: we are not using the external hardware trigger, hence
> we
> >   are likely waiting in a blocked thread waiting for this interrupt to
> >   happen: in this case we just wake up the waiting thread.
> >
> > Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> > ---
> >  drivers/iio/adc/max1027.c | 20 +++++++++++++++++---
> >  1 file changed, 17 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/iio/adc/max1027.c b/drivers/iio/adc/max1027.c
> > index 8d86e77fb5db..8c5995ae59f2 100644
> > --- a/drivers/iio/adc/max1027.c
> > +++ b/drivers/iio/adc/max1027.c
> > @@ -235,6 +235,7 @@ struct max1027_state {
> >  	struct iio_trigger		*trig;
> >  	__be16				*buffer;
> >  	struct mutex			lock;
> > +	bool				data_rdy;
> >  	bool				cnvst_trigger;
> >  	u8				reg ____cacheline_aligned;
> >  };
> > @@ -243,12 +244,22 @@ static
> DECLARE_WAIT_QUEUE_HEAD(max1027_queue);
> >
> >  static int max1027_wait_eoc(struct iio_dev *indio_dev)
> >  {
> > +	struct max1027_state *st = iio_priv(indio_dev);
> >  	unsigned int conversion_time =
> MAX1027_CONVERSION_UDELAY;
> > +	int ret;
> >
> > -	if (indio_dev->active_scan_mask)
> > -		conversion_time *= hweight32(*indio_dev-
> >active_scan_mask);
> > +	if (st->spi->irq) {
> > +		ret =
> wait_event_interruptible_timeout(max1027_queue,
> > +						       st->data_rdy, HZ /
> 1000);
> > +		st->data_rdy = false;
> > +		if (ret == -ERESTARTSYS)
> > +			return ret;
> > +	} else {
> > +		if (indio_dev->active_scan_mask)
> > +			conversion_time *= hweight32(*indio_dev-
> >active_scan_mask);
> >
> > -	usleep_range(conversion_time, conversion_time * 2);
> > +		usleep_range(conversion_time, conversion_time * 2);
> > +	}
> >
> >  	return 0;
> >  }
> > @@ -481,6 +492,9 @@ static irqreturn_t
> max1027_eoc_irq_handler(int irq, void *private)
> >  	if (st->cnvst_trigger) {
> >  		ret = max1027_read_scan(indio_dev);
> >  		iio_trigger_notify_done(indio_dev->trig);
> > +	} else {
> > +		st->data_rdy = true;
> > +		wake_up(&max1027_queue);
> 
> I can't see why a queue is appropriate for this.  Use a completion and
> have
> one per instance of the device.  No need for the flag etc in that case as
> complete() means we have had an interrupt.
> 

In the case that 'st-> cnvst_trigger' is not set but the spi IRQ
is present, we will wait until we get 'wake_up()' called from here. I wonder if
that is a good idea as the device own trigger is not being used. FWIW, I think this
sync logic is a bit confusing... I would still use the normal trigger infrastructure
('iio_trigger_generic_data_rdy_poll()') and use the 'cnvst_trigger' flag in the
trigger handler to manually start conversions + wait till eoc. But I might be missing
something though.

Regarding this handler, I just realized that this is the hard IRQ handler which
might end up calling 'max1027_read_scan()' which in turn calls 'spi_read()'. Am I
missing something here?

- Nuno Sá

  reply	other threads:[~2021-08-30 12:45 UTC|newest]

Thread overview: 71+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-18 11:11 [PATCH 00/16] Bring software triggers support to MAX1027-like ADCs Miquel Raynal
2021-08-18 11:11 ` [PATCH 01/16] iio: adc: max1027: Fix wrong shift with 12-bit devices Miquel Raynal
2021-08-20  7:02   ` Sa, Nuno
2021-08-30  9:57     ` Jonathan Cameron
2021-08-18 11:11 ` [PATCH 02/16] iio: adc: max1027: Fix the number of max1X31 channels Miquel Raynal
2021-08-20  7:03   ` Sa, Nuno
2021-08-30 10:00     ` Jonathan Cameron
2021-08-18 11:11 ` [PATCH 03/16] iio: adc: max1027: Push only the requested samples Miquel Raynal
2021-08-20  7:10   ` Sa, Nuno
2021-08-30 10:07     ` Jonathan Cameron
2021-08-30 10:49       ` Sa, Nuno
2021-08-30 14:29         ` Jonathan Cameron
2021-08-30 15:02           ` Sa, Nuno
2021-09-01  8:12             ` Miquel Raynal
2021-09-04 14:06               ` Jonathan Cameron
2021-09-06  8:59               ` Sa, Nuno
2021-09-06 16:56                 ` Jonathan Cameron
2021-09-06 17:34                   ` Miquel Raynal
2021-08-30 10:06   ` Jonathan Cameron
2021-08-18 11:11 ` [PATCH 04/16] iio: adc: max1027: Lower conversion time Miquel Raynal
2021-08-20  7:12   ` Sa, Nuno
2021-08-30 10:10   ` Jonathan Cameron
2021-08-18 11:11 ` [PATCH 05/16] iio: adc: max1027: Drop extra warning message Miquel Raynal
2021-08-20  7:12   ` Sa, Nuno
2021-08-30 10:12   ` Jonathan Cameron
2021-08-18 11:11 ` [PATCH 06/16] iio: adc: max1027: Rename a helper Miquel Raynal
2021-08-20  7:13   ` Sa, Nuno
2021-08-18 11:11 ` [PATCH 07/16] iio: adc: max1027: Create a helper to configure the trigger Miquel Raynal
2021-08-20  7:16   ` Sa, Nuno
2021-08-30 10:16   ` Jonathan Cameron
2021-08-18 11:11 ` [PATCH 08/16] iio: adc: max1027: Explain better how the trigger state gets changed Miquel Raynal
2021-08-20  7:17   ` Sa, Nuno
2021-08-18 11:11 ` [PATCH 09/16] iio: adc: max1027: Create a helper to configure the channels to scan Miquel Raynal
2021-08-20  7:18   ` Sa, Nuno
2021-08-18 11:11 ` [PATCH 10/16] iio: adc: max1027: Prevent single channel accesses during buffer reads Miquel Raynal
2021-08-20  7:20   ` Sa, Nuno
2021-08-20  7:30     ` Sa, Nuno
2021-08-30 10:20       ` Jonathan Cameron
2021-09-02  8:56         ` Miquel Raynal
2021-08-18 11:11 ` [PATCH 11/16] iio: adc: max1027: Separate the IRQ handler from the read logic Miquel Raynal
2021-08-20  7:23   ` Sa, Nuno
2021-09-02  8:55     ` Miquel Raynal
2021-09-04 14:08       ` Jonathan Cameron
2021-08-18 11:11 ` [PATCH 12/16] iio: adc: max1027: Introduce an end of conversion helper Miquel Raynal
2021-08-20  7:28   ` Sa, Nuno
2021-09-02  9:26     ` Miquel Raynal
2021-08-30 10:34   ` Jonathan Cameron
2021-08-18 11:11 ` [PATCH 13/16] iio: adc: max1027: Prepare re-using the EOC interrupt Miquel Raynal
2021-08-20  7:31   ` Sa, Nuno
2021-08-30 10:30   ` Jonathan Cameron
2021-08-30 10:47   ` Jonathan Cameron
2021-08-18 11:11 ` [PATCH 14/16] iio: adc: max1027: Consolidate the end of conversion helper Miquel Raynal
2021-08-20  7:45   ` Sa, Nuno
2021-08-30 10:37   ` Jonathan Cameron
2021-08-30 12:44     ` Sa, Nuno [this message]
2021-08-30 14:32       ` Jonathan Cameron
2021-09-02 15:12       ` Miquel Raynal
2021-09-03 14:28         ` Sa, Nuno
2021-09-03 14:46           ` Miquel Raynal
2021-09-05  9:41             ` Jonathan Cameron
2021-09-06  9:12               ` Sa, Nuno
2021-09-06  9:30                 ` Sa, Nuno
2021-08-18 11:11 ` [PATCH 15/16] iio: adc: max1027: Support software triggers Miquel Raynal
2021-08-20  7:58   ` Sa, Nuno
2021-09-02 12:25     ` Miquel Raynal
2021-09-03 14:20       ` Sa, Nuno
2021-08-30 10:50   ` Jonathan Cameron
2021-09-02 15:21     ` Miquel Raynal
2021-09-05  9:43       ` Jonathan Cameron
2021-08-18 11:11 ` [PATCH 16/16] iio: adc: max1027: Enable software triggers to be used without IRQ Miquel Raynal
2021-08-30 10:54   ` Jonathan Cameron

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