linux-kernel - Re: [PATCH] iio: dac: ad3530r: Fix incorrect masking for channels 4-7 in powerdown mode

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Message-ID: <c0f4907eb762e618dcf64a6821320f814715be5f.camel@gmail.com>
Date: Fri, 27 Jun 2025 16:54:33 +0100
From: Nuno Sá <noname.nuno@...il.com>
To: Kim Seer Paller <kimseer.paller@...log.com>, Lars-Peter Clausen
	 <lars@...afoo.de>, Michael Hennerich <Michael.Hennerich@...log.com>, 
 Jonathan Cameron
	 <jic23@...nel.org>, David Lechner <dlechner@...libre.com>, Nuno
 Sá
	 <nuno.sa@...log.com>, Andy Shevchenko <andy@...nel.org>
Cc: Jonathan Cameron <Jonathan.Cameron@...wei.com>,
 linux-iio@...r.kernel.org, 	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iio: dac: ad3530r: Fix incorrect masking for channels
 4-7 in powerdown mode

On Thu, 2025-06-26 at 16:38 +0800, Kim Seer Paller wrote:
> In the current implementation of ad3530r_set_dac_powerdown() function,
> the macro AD3530R_OP_MODE_CHAN_MSK(chan->channel) is used to generate
> the bitmask for the operating mode of a specific channel. However, this
> macro does not account for channels 4-7, which map to the second
> register AD3530R_OUTPUT_OPERATING_MODE_1 for the 8 channeled device. As
> a result, the bitmask is incorrectly calculated for these channels,
> leading to improper configuration of the powerdown mode. Resolve this
> issue by adjusting the channel index for channels 4-7 by subtracting 4
> before applying the macro. This ensures that the correct bitmask is
> generated for the second register.
> 
> Fixes: 93583174a3df ("iio: dac: ad3530r: Add driver for AD3530R and AD3531R")
> Signed-off-by: Kim Seer Paller <kimseer.paller@...log.com>
> ---

LGTM,

Reviewed-by: Nuno Sá <nuno.sa@...log.com>

>  drivers/iio/dac/ad3530r.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/dac/ad3530r.c b/drivers/iio/dac/ad3530r.c
> index
> f9752a571aa53ca0d7e199ed6a78550358185bf9..6134613777b8e1d4516109b74e0b3b79edb1
> ae75 100644
> --- a/drivers/iio/dac/ad3530r.c
> +++ b/drivers/iio/dac/ad3530r.c
> @@ -166,7 +166,9 @@ static ssize_t ad3530r_set_dac_powerdown(struct iio_dev
> *indio_dev,
>  	      AD3530R_OUTPUT_OPERATING_MODE_0 :
>  	      AD3530R_OUTPUT_OPERATING_MODE_1;
>  	pdmode = powerdown ? st->chan[chan->channel].powerdown_mode : 0;
> -	mask = AD3530R_OP_MODE_CHAN_MSK(chan->channel);
> +	mask = chan->channel < AD3531R_MAX_CHANNELS ?
> +	       AD3530R_OP_MODE_CHAN_MSK(chan->channel) :
> +	       AD3530R_OP_MODE_CHAN_MSK(chan->channel - 4);
>  	val = field_prep(mask, pdmode);
>  
>  	ret = regmap_update_bits(st->regmap, reg, mask, val);
> 
> ---
> base-commit: 0a2857e778599c2794dc89c40dc79ead631b34df
> change-id: 20250626-bug_fix-404361f2f190
> 
> Best regards,