linux-kernel - Re: [PATCH v2 2/2] iio: accel: adxl380: Optimize reading of FIFO entries in interrupt handler

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Message-ID: <20260122195313.53fde73c@jic23-huawei>
Date: Thu, 22 Jan 2026 19:53:13 +0000
From: Jonathan Cameron <jic23@...nel.org>
To: Francesco Lavra <flavra@...libre.com>
Cc: Ramona Gradinariu <ramona.gradinariu@...log.com>, Antoniu Miclaus
 <antoniu.miclaus@...log.com>, Lars-Peter Clausen <lars@...afoo.de>, Michael
 Hennerich <Michael.Hennerich@...log.com>, David Lechner
 <dlechner@...libre.com>, Nuno Sá <nuno.sa@...log.com>, Andy
 Shevchenko <andy@...nel.org>, linux-iio@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] iio: accel: adxl380: Optimize reading of FIFO
 entries in interrupt handler

On Mon, 19 Jan 2026 11:23:17 +0100
Francesco Lavra <flavra@...libre.com> wrote:

> In order to minimize the time required for transferring FIFO data from the
> sensor to the host machine, perform the read from the FIFO in a single call
> to regmap_bulk_read().
It's a call to regmap_noinc_read()  not regmap_bulk_read()
I'll fix it.

> This allows reading acceleration data for all 3 axes at 16 kHz
> sampling frequency using a 1MHz I2C bus frequency.
> 
> Signed-off-by: Francesco Lavra <flavra@...libre.com>
> ---
>  drivers/iio/accel/adxl380.c | 12 +++++-------
>  1 file changed, 5 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/iio/accel/adxl380.c b/drivers/iio/accel/adxl380.c
> index 650cdbffd4a7..e3e6b182eb3d 100644
> --- a/drivers/iio/accel/adxl380.c
> +++ b/drivers/iio/accel/adxl380.c
> @@ -965,14 +965,12 @@ static irqreturn_t adxl380_irq_handler(int irq, void  *p)
>  		return IRQ_HANDLED;
>  
>  	fifo_entries = rounddown(fifo_entries, st->fifo_set_size);
> -	for (i = 0; i < fifo_entries; i += st->fifo_set_size) {
> -		ret = regmap_noinc_read(st->regmap, ADXL380_FIFO_DATA,
> -					&st->fifo_buf[i],
> -					2 * st->fifo_set_size);
> -		if (ret)
> -			return IRQ_HANDLED;
> +	ret = regmap_noinc_read(st->regmap, ADXL380_FIFO_DATA, &st->fifo_buf,
> +				sizeof(*st->fifo_buf) * fifo_entries);
> +	if (ret)
> +		return IRQ_HANDLED;
> +	for (i = 0; i < fifo_entries; i += st->fifo_set_size)
>  		iio_push_to_buffers(indio_dev, &st->fifo_buf[i]);
> -	}
>  
>  	return IRQ_HANDLED;
>  }