linux-kernel - Re: [PATCH 2/6] iio: adc: ad7173: fix buffers enablement for ad7176-2

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Message-ID: <20240406155646.694f710b@jic23-huawei>
Date: Sat, 6 Apr 2024 15:56:46 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Dumitru Ceclan via B4 Relay
 <devnull+dumitru.ceclan.analog.com@...nel.org>
Cc: dumitru.ceclan@...log.com, Lars-Peter Clausen <lars@...afoo.de>, Michael
 Hennerich <Michael.Hennerich@...log.com>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley
 <conor+dt@...nel.org>, David Lechner <dlechner@...libre.com>,
 linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, Dumitru Ceclan <mitrutzceclan@...il.com>
Subject: Re: [PATCH 2/6] iio: adc: ad7173: fix buffers enablement for
 ad7176-2

On Mon, 01 Apr 2024 18:32:20 +0300
Dumitru Ceclan via B4 Relay <devnull+dumitru.ceclan.analog.com@...nel.org> wrote:

> From: Dumitru Ceclan <dumitru.ceclan@...log.com>
> 
> AD7176-2 does not feature input buffers, enable buffers only on
>  supported models.
> 
> Fixes: cff259bf7274 ("iio: adc: ad7173: fix buffers enablement for ad7176-2")
> Signed-off-by: Dumitru Ceclan <dumitru.ceclan@...log.com>

How bad is this?  If you can find out if writing those bits does anything
harmful (they are reserved and datasheet says should be written 0 I think)
That will help people decide whether to backport the fix?

> ---
>  drivers/iio/adc/ad7173.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad7173.c b/drivers/iio/adc/ad7173.c
> index f6d29abe1d04..8a95b1391826 100644
> --- a/drivers/iio/adc/ad7173.c
> +++ b/drivers/iio/adc/ad7173.c
> @@ -145,6 +145,7 @@ struct ad7173_device_info {
>  	unsigned int id;
>  	char *name;
>  	bool has_temp;
> +	bool has_input_buf;
>  	bool has_int_ref;
>  	bool has_ref2;
>  	u8 num_gpios;
> @@ -212,6 +213,7 @@ static const struct ad7173_device_info ad7173_device_info[] = {
>  		.num_configs = 4,
>  		.num_gpios = 2,
>  		.has_temp = true,
> +		.has_input_buf = true,
>  		.has_int_ref = true,
>  		.clock = 2 * HZ_PER_MHZ,
>  		.sinc5_data_rates = ad7173_sinc5_data_rates,
> @@ -224,6 +226,7 @@ static const struct ad7173_device_info ad7173_device_info[] = {
>  		.num_configs = 8,
>  		.num_gpios = 4,
>  		.has_temp = false,
> +		.has_input_buf = true,
>  		.has_ref2 = true,
>  		.clock = 2 * HZ_PER_MHZ,
>  		.sinc5_data_rates = ad7173_sinc5_data_rates,
> @@ -237,6 +240,7 @@ static const struct ad7173_device_info ad7173_device_info[] = {
>  		.num_configs = 8,
>  		.num_gpios = 4,
>  		.has_temp = true,
> +		.has_input_buf = true,
>  		.has_int_ref = true,
>  		.has_ref2 = true,
>  		.clock = 2 * HZ_PER_MHZ,
> @@ -251,6 +255,7 @@ static const struct ad7173_device_info ad7173_device_info[] = {
>  		.num_configs = 4,
>  		.num_gpios = 2,
>  		.has_temp = true,
> +		.has_input_buf = true,
>  		.has_int_ref = true,
>  		.clock = 16 * HZ_PER_MHZ,
>  		.sinc5_data_rates = ad7175_sinc5_data_rates,
> @@ -263,6 +268,7 @@ static const struct ad7173_device_info ad7173_device_info[] = {
>  		.num_configs = 8,
>  		.num_gpios = 4,
>  		.has_temp = true,
> +		.has_input_buf = true,
>  		.has_int_ref = true,
>  		.has_ref2 = true,
>  		.clock = 16 * HZ_PER_MHZ,
> @@ -289,6 +295,7 @@ static const struct ad7173_device_info ad7173_device_info[] = {
>  		.num_configs = 4,
>  		.num_gpios = 2,
>  		.has_temp = true,
> +		.has_input_buf = true,
>  		.has_int_ref = true,
>  		.clock = 16 * HZ_PER_MHZ,
>  		.odr_start_value = AD7177_ODR_START_VALUE,
> @@ -932,7 +939,7 @@ static int ad7173_fw_parse_channel_config(struct iio_dev *indio_dev)
>  			AD7173_CH_ADDRESS(chan_arr[chan_index].channel,
>  					  chan_arr[chan_index].channel2);
>  		chan_st_priv->cfg.bipolar = false;
> -		chan_st_priv->cfg.input_buf = true;
> +		chan_st_priv->cfg.input_buf = st->info->has_input_buf;
>  		chan_st_priv->cfg.ref_sel = AD7173_SETUP_REF_SEL_INT_REF;
>  		st->adc_mode |= AD7173_ADC_MODE_REF_EN;
>  
> @@ -989,7 +996,7 @@ static int ad7173_fw_parse_channel_config(struct iio_dev *indio_dev)
>  
>  		chan_st_priv->ain = AD7173_CH_ADDRESS(ain[0], ain[1]);
>  		chan_st_priv->chan_reg = chan_index;
> -		chan_st_priv->cfg.input_buf = true;
> +		chan_st_priv->cfg.input_buf = st->info->has_input_buf;
>  		chan_st_priv->cfg.odr = 0;
>  
>  		chan_st_priv->cfg.bipolar = fwnode_property_read_bool(child, "bipolar");
>