From: Cristian Marussi <cristian.marussi@arm.com>
To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Cc: sudeep.holla@arm.com, f.fainelli@gmail.com,
souvik.chakravarty@arm.com, nicola.mazzucato@arm.com,
Cristian Marussi <cristian.marussi@arm.com>
Subject: [RFC PATCH 2/2] hwmon: (scmi) Filter out results wrongly interpreted as negatives
Date: Mon, 20 Dec 2021 17:41:55 +0000 [thread overview]
Message-ID: <20211220174155.40239-3-cristian.marussi@arm.com> (raw)
In-Reply-To: <20211220174155.40239-1-cristian.marussi@arm.com>
SCMI Sensor scmi_reading_get interface can report only unsigned values
while hwmon_ops.read allows for signed negative values to be passed on:
this has the undesired side effect of silently interpreting as negative
any big-enough positive reading reported by the SCMI interface.
Filter out such big positives reporting an error.
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
---
drivers/hwmon/scmi-hwmon.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/drivers/hwmon/scmi-hwmon.c b/drivers/hwmon/scmi-hwmon.c
index b1329a58ce40..0924d1b8a9ce 100644
--- a/drivers/hwmon/scmi-hwmon.c
+++ b/drivers/hwmon/scmi-hwmon.c
@@ -73,10 +73,24 @@ static int scmi_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
struct scmi_sensors *scmi_sensors = dev_get_drvdata(dev);
sensor = *(scmi_sensors->info[type] + channel);
+ /*
+ * Can fail with EIO if the backing SCMI Sensor FW version tried to
+ * report a negative value.
+ */
ret = sensor_ops->reading_get(scmi_sensors->ph, sensor->id, &value);
if (ret)
return ret;
+ /*
+ * Cannot accept either valid positive values so big that would be
+ * interpreted as negative by HWMON signed long *val return value.
+ */
+ if (value & BIT(63)) {
+ dev_warn_once(dev,
+ "Reported unsigned value too big.\n");
+ return -EIO;
+ }
+
ret = scmi_hwmon_scale(sensor, &value);
if (!ret)
*val = value;
--
2.17.1
next prev parent reply other threads:[~2021-12-20 17:42 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-20 17:41 [RFC PATCH 0/2] Sensor readings fixes Cristian Marussi
2021-12-20 17:41 ` [RFC PATCH 1/2] firmware: arm_scmi: Filter out negative results on scmi_reading_get Cristian Marussi
2021-12-20 17:41 ` Cristian Marussi [this message]
2022-03-25 11:41 ` [RFC PATCH 0/2] Sensor readings fixes Cristian Marussi
2022-03-25 21:38 ` Florian Fainelli
2022-03-30 14:43 ` Cristian Marussi
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