linux-kernel - Re: [PATCH v3 2/2] iio: adc: ti-ads1298: Add driver

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Date: Tue, 6 Feb 2024 15:47:45 +0100
From: Mike Looijmans <mike.looijmans@...ic.nl>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
CC: devicetree@...r.kernel.org, linux-iio@...r.kernel.org,
 Jonathan Cameron <jic23@...nel.org>, Lars-Peter Clausen <lars@...afoo.de>,
 Liam Beguin <liambeguin@...il.com>, Liam Girdwood <lgirdwood@...il.com>,
 Maksim Kiselev <bigunclemax@...il.com>,
 Marcus Folkesson <marcus.folkesson@...il.com>,
 Marius Cristea <marius.cristea@...rochip.com>,
 Mark Brown <broonie@...nel.org>, Niklas Schnelle <schnelle@...ux.ibm.com>,
 Okan Sahin <okan.sahin@...log.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/2] iio: adc: ti-ads1298: Add driver

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;
     }
}

-- 
Mike Looijmans
System Expert

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