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Date: Tue, 6 Feb 2024 17:09:16 +0200
From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Mike Looijmans <mike.looijmans@topic.nl>
Cc: devicetree@vger.kernel.org, linux-iio@vger.kernel.org,
	Jonathan Cameron <jic23@kernel.org>,
	Lars-Peter Clausen <lars@metafoo.de>,
	Liam Beguin <liambeguin@gmail.com>,
	Liam Girdwood <lgirdwood@gmail.com>,
	Maksim Kiselev <bigunclemax@gmail.com>,
	Marcus Folkesson <marcus.folkesson@gmail.com>,
	Marius Cristea <marius.cristea@microchip.com>,
	Mark Brown <broonie@kernel.org>,
	Niklas Schnelle <schnelle@linux.ibm.com>,
	Okan Sahin <okan.sahin@analog.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 2/2] iio: adc: ti-ads1298: Add driver
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On Tue, Feb 06, 2024 at 03:47:45PM +0100, Mike Looijmans wrote:
> On 06-02-2024 15:25, Mike Looijmans wrote:
> > On 06-02-2024 14:50, Andy Shevchenko wrote:
> > > On Tue, Feb 06, 2024 at 02:33:47PM +0100, Mike Looijmans wrote:
> > > > On 06-02-2024 13:57, Andy Shevchenko wrote:
> > > > > On Tue, Feb 06, 2024 at 07:58:18AM +0100, Mike Looijmans wrote:

..

> > > > > > +??? wasbusy = --priv->rdata_xfer_busy;
> > > > > Why preincrement? How would it be different from postincrement?
> > > > Maybe better write this as:
> > > > 
> > > > --priv->rdata_xfer_busy;
> > > > 
> > > > wasbusy = priv->rdata_xfer_busy;
> > > > 
> > > > I want the value after decrementing it.
> > > Yes, looks more obvious.
> > 
> > Having done that, and looking at it again, it's better to just eliminate
> > the local "wasbusy" altogether. More concise.
> 
> 
> This removes the decrement operator, so the method now looks like this:
> 
> 
> static void ads1298_rdata_release_busy_or_restart(struct ads1298_private
> *priv)
> {
> ?? ?guard(spinlock_irqsave)(&priv->irq_busy_lock);
> 
> ?? ?if (priv->rdata_xfer_busy > 1) {
> ?? ???? /*
> ?? ???? ?* DRDY interrupt occurred before SPI completion. Start a new
> ?? ???? ?* SPI transaction now to retrieve the data that wasn't latched
> ?? ???? ?* into the ADS1298 chip's transfer buffer yet.
> ?? ???? ?*/
> ?? ???? spi_async(priv->spi, &priv->rdata_msg);
> ?? ???? /*
> ?? ???? ?* If more than one DRDY took place, there was an overrun. Since
> ?? ???? ?* the sample is already lost, reset the counter to 1 so that
> ?? ???? ?* we will wait for a DRDY interrupt after this SPI transaction.
> ?? ???? ?*/
> ?? ???? priv->rdata_xfer_busy = 1;
> ?? ?} else {
> ?? ???? /* No pending data, wait for DRDY */
> ?? ???? priv->rdata_xfer_busy = 0;
> ?? ?}
> }

Yep and it looks like you reinvented atomics :-)

	atomic_t rdata_xfer_busy;
	...

But it's up to you what to do with that.
Maybe Jonathan can advice something different.

-- 
With Best Regards,
Andy Shevchenko