Re: [PATCH v2] hwmon: (pmbus_core) Check adapter PEC support

[Guenter Roeck]

On Sat, Jun 05, 2021 at 07:27:02AM +0200, Paul Menzel wrote:
> From: Madhava Reddy Siddareddygari <msiddare@xxxxxxxxx>
> 
> Currently, for Packet Error Checking (PEC) only the controller
> is checked for support. This causes problems on the cisco-8000
> platform where a SMBUS transaction errors are observed. This is
> because PEC has to be enabled only if both controller and
> adapter support it.
> 
> Added code to check PEC capability for adapter and enable it
> only if both controller and adapter supports PEC.
> 
> Signed-off-by: Madhava Reddy Siddareddygari <msiddare@xxxxxxxxx>
> [Upstream from SONiC https://github.com/Azure/sonic-linux-kernel/pull/215]
> Signed-off-by: Paul Menzel <pmenzel@xxxxxxxxxxxxx>

Applied.

Thanks,
Guenter

> ---
> v2: Do not revert check introduced by commit e5befc02 (hwmon: (pmbus)
>     Add a PMBUS_NO_CAPABILITY platform data flag).
> 
>  drivers/hwmon/pmbus/pmbus_core.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
> index bbd745178147..2fd0fec59d4f 100644
> --- a/drivers/hwmon/pmbus/pmbus_core.c
> +++ b/drivers/hwmon/pmbus/pmbus_core.c
> @@ -2214,11 +2214,15 @@ static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data,
>  		data->has_status_word = true;
>  	}
>  
> -	/* Enable PEC if the controller supports it */
> +	/* Enable PEC if the controller and bus supports it */
>  	if (!(data->flags & PMBUS_NO_CAPABILITY)) {
>  		ret = i2c_smbus_read_byte_data(client, PMBUS_CAPABILITY);
> -		if (ret >= 0 && (ret & PB_CAPABILITY_ERROR_CHECK))
> -			client->flags |= I2C_CLIENT_PEC;
> +		if (ret >= 0 && (ret & PB_CAPABILITY_ERROR_CHECK)) {
> +			if (i2c_check_functionality(client->adapter,
> +						I2C_FUNC_SMBUS_PEC)) {
> +				client->flags |= I2C_CLIENT_PEC;
> +			}
> +		}
>  	}
>  
>  	/*