linux-kernel - Re: [PATCH] hwmon: (pmbus/mp2975) Fix PGOOD in READ_STATUS

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Date:   Fri, 28 Jul 2023 03:00:27 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Naresh Solanki <naresh.solanki@...ements.com>,
        Jean Delvare <jdelvare@...e.com>,
        krzysztof.kozlowski+dt@...aro.org
Cc:     linux-hwmon@...r.kernel.org,
        Patrick Rudolph <patrick.rudolph@...ements.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] hwmon: (pmbus/mp2975) Fix PGOOD in READ_STATUS_WORD

On 7/28/23 01:25, Naresh Solanki wrote:
> From: Patrick Rudolph <patrick.rudolph@...ements.com>
> 
> MPS returns PGOOD instead of PB_STATUS_POWER_GOOD_N.
> Fix that in the read_word_data hook.
> 
Datasheets are not public, so I can not verify, but the code below
only handles MP2973 and MP2971. What about MP2975 ?

Either case, this appears to affect most Monolithic chips, but
not all of them. Please limit the statement to known to be affected
chips.

> Signed-off-by: Patrick Rudolph <patrick.rudolph@...ements.com>
> Signed-off-by: Naresh Solanki <Naresh.Solanki@...ements.com>
> ---
>   drivers/hwmon/pmbus/mp2975.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/hwmon/pmbus/mp2975.c b/drivers/hwmon/pmbus/mp2975.c
> index 28f33f4618fa..410b6eae6d02 100644
> --- a/drivers/hwmon/pmbus/mp2975.c
> +++ b/drivers/hwmon/pmbus/mp2975.c
> @@ -297,6 +297,10 @@ static int mp2973_read_word_data(struct i2c_client *client, int page,
>   	int ret;
>   
>   	switch (reg) {
> +	case PMBUS_STATUS_WORD:
> +		ret = pmbus_read_word_data(client, page, phase, reg);

		if (ret < 0)
			return ret;

Please add a comment explaining what is going on.

> +		ret ^= PB_STATUS_POWER_GOOD_N;
> +		break;
>   	case PMBUS_OT_FAULT_LIMIT:
>   		ret = mp2975_read_word_helper(client, page, phase, reg,
>   					      GENMASK(7, 0));
> 
> base-commit: a4bb1ce5b9e3ca403c04e20ebeae77fd6447cb11