linux-kernel - Re: [PATCH] iio: adc: ad7606: fix serial register access

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Message-ID: <20250418165649.64ebef8b@jic23-huawei>
Date: Fri, 18 Apr 2025 16:56:49 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Angelo Dureghello <adureghello@...libre.com>
Cc: 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>,
 Beniamin Bia <beniamin.bia@...log.com>, Jonathan Cameron
 <Jonathan.Cameron@...wei.com>, linux-iio@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iio: adc: ad7606: fix serial register access

On Thu, 17 Apr 2025 23:42:51 +0200
Angelo Dureghello <adureghello@...libre.com> wrote:

> From: Angelo Dureghello <adureghello@...libre.com>
> 
> Fix register read/write routine as per datasheet.
> 
> When reading multiple consecutive registers, only the first one is read
> properly. This is due to missing chip select between first and second
> 16bit transfer.
In what sense of missing? Given code you mean missing being unselected
briefly between transfers I think.

chip select itself is always set in current code and hence the 'missing'
description had me confused!

Anyhow, looks fine to me but I'd like this on list a little longer before
I pick it up.

Thanks,

Jonathan

> Add chip select between the two 16bit transfers as per datasheet
> AD7606C-16, rev 0, figure 110.
> 
> Fixes: f2a22e1e172f ("iio: adc: ad7606: Add support for software mode for ad7616")
> Signed-off-by: Angelo Dureghello <adureghello@...libre.com>
> ---
>  drivers/iio/adc/ad7606_spi.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/adc/ad7606_spi.c b/drivers/iio/adc/ad7606_spi.c
> index 997be483ebb93293481b922e13ece4edb47e940a..bd05357a542cf7234d5bb6b718829d6b720262cd 100644
> --- a/drivers/iio/adc/ad7606_spi.c
> +++ b/drivers/iio/adc/ad7606_spi.c
> @@ -103,7 +103,7 @@ static int ad7606_spi_reg_read(struct ad7606_state *st, unsigned int addr)
>  		{
>  			.tx_buf = &st->d16[0],
>  			.len = 2,
> -			.cs_change = 0,
> +			.cs_change = 1,
>  		}, {
>  			.rx_buf = &st->d16[1],
>  			.len = 2,
> 
> ---
> base-commit: 8dc6b228d746b1a900bed28568defb2266fa4c43
> change-id: 20250417-wip-bl-ad7606-fix-reg-access-729c21478d1f
> 
> Best regards,