linux-kernel - Re: [PATCH] hwmod: (pmbus) disable PEC if not enabled

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Message-ID: <3da420df-234e-4701-2182-1f043b9ccc56@roeck-us.net>
Date:   Wed, 20 Apr 2022 06:55:52 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Adam Wujek <dev_public@...ek.eu>
Cc:     Jean Delvare <jdelvare@...e.com>, linux-hwmon@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] hwmod: (pmbus) disable PEC if not enabled

On 4/20/22 05:54, Adam Wujek wrote:
> Explicitly disable PEC when the client does not support it.
> The problematic scenario is the following. A device with enabled PEC
> support is up and running, a kernel driver loaded.
> Then the driver is unloaded (or device unbound), the HW device
> is reconfigured externally (e.g. by i2cset) to advertise itself as not
> supporting PEC. Without a new code, at the second load of the driver
> (or bind) the "flags" variable is not updated to avoid PEC usage. As a
> consequence the further communication with the device is done with
> the PEC enabled, which is wrong.
> 
> Signed-off-by: Adam Wujek <dev_public@...ek.eu>

Subject should start with hwmon:. Please version your patches,
and provide change logs.

> ---
>   drivers/hwmon/pmbus/pmbus_core.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
> index b2618b1d529e..0af7a3d74f47 100644
> --- a/drivers/hwmon/pmbus/pmbus_core.c
> +++ b/drivers/hwmon/pmbus/pmbus_core.c
> @@ -2334,7 +2334,8 @@ static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data,
>   				client->flags |= I2C_CLIENT_PEC;
>   			}
>   		}
> -	}
> +	} else
> +		client->flags &= ~I2C_CLIENT_PEC;

Since if() is in {}, else should be in {} as well.

Guenter

> 
>   	/*
>   	 * Check if the chip is write protected. If it is, we can not clear
> --
> 2.25.1
> 
>