Re: [PATCH v2 1/1] hwmon (occ): Add temp sensor value check

[Eddie James <eajames@linux.ibm.com>]

On 4/17/19 1:03 PM, Alexander Amelkin wrote:
> From: Alexander Soldatov <a.soldatov@yadro.com>
>
> The occ driver supports two formats for the temp sensor value.
>
> The OCC firmware for P8 supports only the first format, for which
> no range checking or error processing is performed in the driver.
> Inspecting the OCC sources for P8 reveals that OCC may send
> a special value 0xFFFF to indicate that a sensor read timeout
> has occurred, see
>
> https://github.com/open-power/occ/blob/master_p8/src/occ/cmdh/cmdh_fsp_cmds.c#L395
>
> That situation wasn't handled in the driver. This patch adds invalid
> temp value check for the sensor data format 1 and handles it the same
> way as it is done for the format 2, where EREMOTEIO is reported for
> this case.


Thanks Alexander and Guenter.


Reviewed-by: Eddie James <eajames@linux.ibm.com>


>
> Signed-off-by: Alexander Soldatov <a.soldatov@yadro.com>
> Signed-off-by: Alexander Amelkin <a.amelkin@yadro.com>
> Reviewed-by: Alexander Amelkin <a.amelkin@yadro.com>
> Cc: Edward A. James <eajames@us.ibm.com>
> Cc: Joel Stanley <joel@jms.id.au>
> ---
>   drivers/hwmon/occ/common.c | 4 ++++
>   1 file changed, 4 insertions(+)
>
> diff --git a/drivers/hwmon/occ/common.c b/drivers/hwmon/occ/common.c
> index 4679acb..825631c 100644
> --- a/drivers/hwmon/occ/common.c
> +++ b/drivers/hwmon/occ/common.c
> @@ -235,6 +235,12 @@ static ssize_t occ_show_temp_1(struct device *dev,
>   		val = get_unaligned_be16(&temp->sensor_id);
>   		break;
>   	case 1:
> +		/*
> +		 * If a sensor reading has expired and couldn't be refreshed,
> +		 * OCC returns 0xFFFF for that sensor.
> +		 */
> +		if (temp->value == 0xFFFF)
> +			return -EREMOTEIO;
>   		val = get_unaligned_be16(&temp->value) * 1000;
>   		break;
>   	default: