linux-kernel - Re: [PATCH v3 06/10] iio: adc: ad4170: Add support for buffered data capture

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Message-ID: <20250525114610.532f14a1@jic23-huawei>
Date: Sun, 25 May 2025 11:46:10 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Marcelo Schmitt <marcelo.schmitt@...log.com>
Cc: <linux-iio@...r.kernel.org>, <devicetree@...r.kernel.org>,
 <linux-gpio@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
 <lars@...afoo.de>, <Michael.Hennerich@...log.com>, <dlechner@...libre.com>,
 <nuno.sa@...log.com>, <andy@...nel.org>, <robh@...nel.org>,
 <krzk+dt@...nel.org>, <conor+dt@...nel.org>, <linus.walleij@...aro.org>,
 <brgl@...ev.pl>, <marcelo.schmitt1@...il.com>
Subject: Re: [PATCH v3 06/10] iio: adc: ad4170: Add support for buffered
 data capture

On Tue, 13 May 2025 09:35:23 -0300
Marcelo Schmitt <marcelo.schmitt@...log.com> wrote:

> Extend the AD4170 driver to allow buffered data capture in continuous read
> mode. In continuous read mode, the chip skips the instruction phase and
> outputs just ADC sample data, enabling faster sample rates to be reached.
> The internal channel sequencer always starts sampling from channel 0 and
> channel 0 must be enabled if more than one channel is selected for data
> capture. The scan mask validation callback checks if the aforementioned
> condition is met.
> 
> Signed-off-by: Marcelo Schmitt <marcelo.schmitt@...log.com>

I'm curious - why no timestamps?

> diff --git a/drivers/iio/adc/ad4170.c b/drivers/iio/adc/ad4170.c
> index 218f768042fe..e8856c911dfd 100644
> --- a/drivers/iio/adc/ad4170.c
> +++ b/drivers/iio/adc/ad4170.c

>  
>  enum ad4170_ref_buf {
> @@ -309,9 +322,13 @@ struct ad4170_state {
>  	struct spi_device *spi;
>  	struct regmap *regmap;
>  	int sps_tbl[ARRAY_SIZE(ad4170_filt_names)][AD4170_MAX_FS_TBL_SIZE][2];
> +	__be32 bounce_buffer[AD4170_MAX_CHANNELS];
> +	struct spi_message msg;
> +	struct spi_transfer xfer;
> +	struct iio_trigger *trig;
> +	struct completion completion;
>  	int pins_fn[AD4170_NUM_ANALOG_PINS];
>  	u32 int_pin_sel;
> -	struct completion completion;

Probably better to move this to it's new location when it's introduced and
reduce noise a little here.

>  	/*