linux-kernel - Re: [PATCH] hwmon: (nct6683) Add another chip ID for NCT6687D sensor chip found on some MSI boards.

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Date:   Mon, 15 May 2023 06:19:58 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     llyyr <llyyr.public@...il.com>
Cc:     Jean Delvare <jdelvare@...e.com>, linux-hwmon@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] hwmon: (nct6683) Add another chip ID for NCT6687D sensor
 chip found on some MSI boards.

On Mon, May 15, 2023 at 02:55:46PM +0530, llyyr wrote:
> This value was found on MSI Z690-A PRO DDR5, with a NCT6687D chip.
> 
> Signed-off-by: llyyr <llyyr.public@...il.com>
> ---
>  drivers/hwmon/nct6683.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/hwmon/nct6683.c b/drivers/hwmon/nct6683.c
> index a872f783e..5df9b9ce7 100644
> --- a/drivers/hwmon/nct6683.c
> +++ b/drivers/hwmon/nct6683.c
> @@ -14,6 +14,7 @@
>   * nct6683d     21(1)   16      8       32(1) 0xc730
>   * nct6686d     21(1)   16      8       32(1) 0xd440
>   * nct6687d     21(1)   16      8       32(1) 0xd590
> + *                                           (0xd592)
>   *
>   * Notes:
>   *	(1) Total number of vin and temp inputs is 32.
> @@ -71,6 +72,7 @@ static const char * const nct6683_chip_names[] = {
>  #define SIO_NCT6683_ID		0xc730
>  #define SIO_NCT6686_ID		0xd440
>  #define SIO_NCT6687_ID		0xd590
> +#define SIO_NCT6687_ID2		0xd592
>  #define SIO_ID_MASK		0xFFF0
>  
>  static inline void
> @@ -1362,6 +1364,7 @@ static int __init nct6683_find(int sioaddr, struct nct6683_sio_data *sio_data)
>  		sio_data->kind = nct6686;
>  		break;
>  	case SIO_NCT6687_ID:
> +	case SIO_NCT6687_ID2:
>  		sio_data->kind = nct6687;
>  		break;

The checked value is masked with SIO_ID_MASK, or 0xfff0. Why would it be
necessary or even make sense to compare that masked value with 0xd592 ?
Please provide evidence that and why this code is needed.

Guenter