linux-kernel - Re: [PATCH] hwmon (occ): Add temp sensor value check

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Date:   Wed, 10 Jul 2019 13:56:05 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Joel Stanley <joel@....id.au>
Cc:     linux-hwmon@...r.kernel.org, Eddie James <eajames@...ux.ibm.com>,
        Alexander Amelkin <a.amelkin@...ro.com>,
        Lei YU <mine260309@...il.com>,
        Alexander Soldatov <a.soldatov@...ro.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] hwmon (occ): Add temp sensor value check

On Wed, Jul 10, 2019 at 04:56:06PM +0930, Joel Stanley wrote:
> From: Alexander Soldatov <a.soldatov@...ro.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.
> 
> Fixes: 54076cb3b5ff ("hwmon (occ): Add sensor attributes and register hwmon device")
> Signed-off-by: Alexander Soldatov <a.soldatov@...ro.com>
> Signed-off-by: Alexander Amelkin <a.amelkin@...ro.com>
> Reviewed-by: Alexander Amelkin <a.amelkin@...ro.com>
> Reviewed-by: Eddie James <eajames@...ux.ibm.com>
> Signed-off-by: Joel Stanley <joel@....id.au>

Applied.

Thanks,
Guenter

> ---
>  drivers/hwmon/occ/common.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/hwmon/occ/common.c b/drivers/hwmon/occ/common.c
> index cccf91742c1a..a7d2b16dd702 100644
> --- a/drivers/hwmon/occ/common.c
> +++ b/drivers/hwmon/occ/common.c
> @@ -241,6 +241,12 @@ 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: