linux-kernel - Re: [PATCH v2 3/8] iio: at91_adc: pass ref to IIO device via param for int function

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Message-ID: <20200516181749.243c9515@archlinux>
Date:   Sat, 16 May 2020 18:17:49 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Alexandru Ardelean <alexandru.ardelean@...log.com>
Cc:     <linux-iio@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-kernel@...r.kernel.org>, <ludovic.desroches@...rochip.com>,
        <eugen.hristev@...rochip.com>, <nicolas.ferre@...rochip.com>,
        <alexandre.belloni@...tlin.com>, <alexandre.torgue@...com>,
        <mcoquelin.stm32@...il.com>, <ak@...klinger.de>
Subject: Re: [PATCH v2 3/8] iio: at91_adc: pass ref to IIO device via param
 for int function

On Thu, 14 May 2020 16:17:05 +0300
Alexandru Ardelean <alexandru.ardelean@...log.com> wrote:

> Since there will be some changes to how iio_priv_to_dev() is implemented,
> it could be that the helper becomes a bit slower, as it will be hidden away
> in the IIO core.
> 
> For this driver, the IIO device can be passed directly as a parameter to
> the at91_ts_sample() function, thus making it immune to the change of
> iio_priv_to_dev().
> The function gets called in an interrupt context.
> 
> Signed-off-by: Alexandru Ardelean <alexandru.ardelean@...log.com>
I wonder. Should we just pass the struct device?  It's only used for
error printing I think, so we could make that explicit.

I'm not that bothered either way though.

Jonathan

> ---
>  drivers/iio/adc/at91_adc.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c
> index 0368b6dc6d60..5999defe47cd 100644
> --- a/drivers/iio/adc/at91_adc.c
> +++ b/drivers/iio/adc/at91_adc.c
> @@ -287,13 +287,12 @@ static void handle_adc_eoc_trigger(int irq, struct iio_dev *idev)
>  	}
>  }
>  
> -static int at91_ts_sample(struct at91_adc_state *st)
> +static int at91_ts_sample(struct iio_dev *idev, struct at91_adc_state *st)
>  {
>  	unsigned int xscale, yscale, reg, z1, z2;
>  	unsigned int x, y, pres, xpos, ypos;
>  	unsigned int rxp = 1;
>  	unsigned int factor = 1000;
> -	struct iio_dev *idev = iio_priv_to_dev(st);
>  
>  	unsigned int xyz_mask_bits = st->res;
>  	unsigned int xyz_mask = (1 << xyz_mask_bits) - 1;
> @@ -449,7 +448,7 @@ static irqreturn_t at91_adc_9x5_interrupt(int irq, void *private)
>  
>  		if (status & AT91_ADC_ISR_PENS) {
>  			/* validate data by pen contact */
> -			at91_ts_sample(st);
> +			at91_ts_sample(idev, st);
>  		} else {
>  			/* triggered by event that is no pen contact, just read
>  			 * them to clean the interrupt and discard all.