mlxsw: core: Add validation of transceiver temperature thresholds

[ Upstream commit 57726ebe2733891c9f59105eff028735f73d05fb ]

Validate thresholds to avoid a single failure due to some transceiver
unreliability. Ignore the last readouts in case warning temperature is
above alarm temperature, since it can cause unexpected thermal
shutdown. Stay with the previous values and refresh threshold within
the next iteration.

This is a rare scenario, but it was observed at a customer site.

Fixes: 6a79507cfe94 ("mlxsw: core: Extend thermal module with per QSFP module thermal zones")
Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/ethernet/mellanox/mlxsw/core_thermal.c b/drivers/net/ethernet/mellanox/mlxsw/core_thermal.c
index 71c90c8a9e943136a2ae5958574d8073c51bd36b..61b99e390353bcbfced5755661f1dfc945d3deea 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlxsw/core_thermal.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/core_thermal.c
@@ -177,6 +177,12 @@ mlxsw_thermal_module_trips_update(struct device *dev, struct mlxsw_core *core,
        if (err)
                return err;
 
+       if (crit_temp > emerg_temp) {
+               dev_warn(dev, "%s : Critical threshold %d is above emergency threshold %d\n",
+                        tz->tzdev->type, crit_temp, emerg_temp);
+               return 0;
+       }
+
        /* According to the system thermal requirements, the thermal zones are
         * defined with four trip points. The critical and emergency
         * temperature thresholds, provided by QSFP module are set as "active"
@@ -191,11 +197,8 @@ mlxsw_thermal_module_trips_update(struct device *dev, struct mlxsw_core *core,
                tz->trips[MLXSW_THERMAL_TEMP_TRIP_NORM].temp = crit_temp;
        tz->trips[MLXSW_THERMAL_TEMP_TRIP_HIGH].temp = crit_temp;
        tz->trips[MLXSW_THERMAL_TEMP_TRIP_HOT].temp = emerg_temp;
-       if (emerg_temp > crit_temp)
-               tz->trips[MLXSW_THERMAL_TEMP_TRIP_CRIT].temp = emerg_temp +
+       tz->trips[MLXSW_THERMAL_TEMP_TRIP_CRIT].temp = emerg_temp +
                                        MLXSW_THERMAL_MODULE_TEMP_SHIFT;
-       else
-               tz->trips[MLXSW_THERMAL_TEMP_TRIP_CRIT].temp = emerg_temp;
 
        return 0;
 }