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From: Jonathan Cameron <jic23@kernel.org>
To: "Sa, Nuno" <Nuno.Sa@analog.com>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>,
	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 15:32:27 +0100	[thread overview]
Message-ID: <20210830153227.7f5809d1@jic23-huawei> (raw)
In-Reply-To: <MW4PR03MB6363F50DC6A4B5D682BA16E299CB9@MW4PR03MB6363.namprd03.prod.outlook.com>

On Mon, 30 Aug 2021 12:44:48 +0000
"Sa, Nuno" <Nuno.Sa@analog.com> wrote:

> > -----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?
Good point.  This will need to be the threaded handler if done like this.

J

> 
> - Nuno Sá


  reply	other threads:[~2021-08-30 14:29 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
2021-08-30 14:32       ` Jonathan Cameron [this message]
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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