Re: [PATCH 8/9] iio: adc: ad_sigma_delta: add SPI offload support

[David Lechner]

On 6/22/25 10:00 AM, Jonathan Cameron wrote:
> On Fri, 20 Jun 2025 17:20:14 -0500
> David Lechner <dlechner@xxxxxxxxxxxx> wrote:
> 
>> Add SPI offload support to the ad_sigma_delta module.
>>

...

>> @@ -670,7 +700,8 @@ static irqreturn_t ad_sd_data_rdy_trig_poll(int irq, void *private)
>>  	if ((!sigma_delta->rdy_gpiod || gpiod_get_value(sigma_delta->rdy_gpiod)) &&
>>  	    ad_sd_disable_irq(sigma_delta)) {
>>  		complete(&sigma_delta->completion);
>> -		iio_trigger_poll(sigma_delta->trig);
>> +		if (sigma_delta->trig)
> 
> Is this defensive or can we actually get here with out a trigger?
> I would have thought in the offload case (so no trigger here) we'd not call this
> function at all.  Mind you, can't we get here with no trigger when doing
> a calibration or simple read normally?  

The difference is that with SPI offload, sigma_delta->trig is NULL
but without SPI offload, it is never NULL. iio_trigger_poll() doesn't
check for NULL and would crash with NULL pointer dereference.

During calibration and single conversion the poll function isn't
attached to the trigger, so I guess that is why it didn't really
hurt to call iio_trigger_poll() in that case.

> 
>> +			iio_trigger_poll(sigma_delta->trig);
>>  
>>  		return IRQ_HANDLED;
>>  	}
> 
>