linux-kernel - Re: [PATCH v4 1/5] hwmon: (pmbus/pim4328) Add new pmbus flag NO_WRITE

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Message-ID: <20210602121248.GB2901466@roeck-us.net>
Date:   Wed, 2 Jun 2021 05:12:48 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Erik Rosen <erik.rosen@...ormote.com>
Cc:     Jean Delvare <jdelvare@...e.com>, Jonathan Corbet <corbet@....net>,
        Daniel Nilsson <daniel.nilsson@...x.com>,
        linux-hwmon@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 1/5] hwmon: (pmbus/pim4328) Add new pmbus flag
 NO_WRITE_PROTECT

On Tue, Jun 01, 2021 at 06:43:16PM +0200, Erik Rosen wrote:
> Some PMBus chips respond with invalid data when reading the WRITE_PROTECT
> register. For such chips, this flag should be set so that the PMBus core
> driver doesn't use the WRITE_PROTECT command to determine it's behavior.
> 
> Signed-off-by: Erik Rosen <erik.rosen@...ormote.com>

Couple of nits, otherwise, for my reference,

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

> ---
>  drivers/hwmon/pmbus/pmbus_core.c | 9 ++++++---
>  include/linux/pmbus.h            | 9 +++++++++
>  2 files changed, 15 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
> index bbd745178147..cb885efc4fba 100644
> --- a/drivers/hwmon/pmbus/pmbus_core.c
> +++ b/drivers/hwmon/pmbus/pmbus_core.c
> @@ -2226,9 +2226,12 @@ static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data,
>  	 * faults, and we should not try it. Also, in that case, writes into
>  	 * limit registers need to be disabled.
>  	 */
> -	ret = i2c_smbus_read_byte_data(client, PMBUS_WRITE_PROTECT);
> -	if (ret > 0 && (ret & PB_WP_ANY))
> -		data->flags |= PMBUS_WRITE_PROTECTED | PMBUS_SKIP_STATUS_CHECK;
> +	if (!(data->flags & PMBUS_NO_WRITE_PROTECT)) {
> +		ret = i2c_smbus_read_byte_data(client, PMBUS_WRITE_PROTECT);
> +		if (ret > 0 && (ret & PB_WP_ANY))
> +			data->flags |= PMBUS_WRITE_PROTECTED
> +				    | PMBUS_SKIP_STATUS_CHECK;

Line length limit is now 100 columns, thus the line split above is not needed.

> +	}
>  
>  	if (data->info->pages)
>  		pmbus_clear_faults(client);
> diff --git a/include/linux/pmbus.h b/include/linux/pmbus.h
> index 12cbbf305969..f720470b1bab 100644
> --- a/include/linux/pmbus.h
> +++ b/include/linux/pmbus.h
> @@ -43,6 +43,15 @@
>   */
>  #define PMBUS_NO_CAPABILITY			BIT(2)
>  
> +/*
> + * PMBUS_NO_WRITE_PROTECT
> + *
> + * Some PMBus chips respond with invalid data when reading the WRITE_PROTECT
> + * register. For such chips, this flag should be set so that the PMBus core
> + * driver doesn't use the WRITE_PROTECT command to determine it's behavior.

its

> + */
> +#define PMBUS_NO_WRITE_PROTECT			BIT(4)
> +
>  struct pmbus_platform_data {
>  	u32 flags;		/* Device specific flags */
>  
> -- 
> 2.20.1
>