mlxsw: reg: Limit MTBR register payload to a single data record

The MTBR register is used to read temperatures from multiple sensors in
one transaction, but the driver only reads from a single sensor in each
transaction.

Rrestrict the payload size of the MTBR register to prevent the
transmission of redundant data to the firmware.
Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/core_env.c

@@ -775,7 +775,7 @@ static int mlxsw_env_module_has_temp_sensor(struct mlxsw_core *mlxsw_core,
 	int err;
 
 	mlxsw_reg_mtbr_pack(mtbr_pl, slot_index,
-			    MLXSW_REG_MTBR_BASE_MODULE_INDEX + module, 1);
+			    MLXSW_REG_MTBR_BASE_MODULE_INDEX + module);
 	err = mlxsw_reg_query(mlxsw_core, MLXSW_REG(mtbr), mtbr_pl);
 	if (err)
 		return err;

drivers/net/ethernet/mellanox/mlxsw/core_hwmon.c

@@ -293,7 +293,7 @@ static ssize_t mlxsw_hwmon_module_temp_fault_show(struct device *dev,
 
 	module = mlxsw_hwmon_attr->type_index - mlxsw_hwmon_dev->sensor_count;
 	mlxsw_reg_mtbr_pack(mtbr_pl, mlxsw_hwmon_dev->slot_index,
-			    MLXSW_REG_MTBR_BASE_MODULE_INDEX + module, 1);
+			    MLXSW_REG_MTBR_BASE_MODULE_INDEX + module);
 	err = mlxsw_reg_query(mlxsw_hwmon->core, MLXSW_REG(mtbr), mtbr_pl);
 	if (err) {
 		dev_err(dev, "Failed to query module temperature sensor\n");

drivers/net/ethernet/mellanox/mlxsw/reg.h

@@ -9551,7 +9551,7 @@ MLXSW_ITEM_BIT_ARRAY(reg, mtwe, sensor_warning, 0x0, 0x10, 1);
 #define MLXSW_REG_MTBR_ID 0x900F
 #define MLXSW_REG_MTBR_BASE_LEN 0x10 /* base length, without records */
 #define MLXSW_REG_MTBR_REC_LEN 0x04 /* record length */
-#define MLXSW_REG_MTBR_REC_MAX_COUNT 47 /* firmware limitation */
+#define MLXSW_REG_MTBR_REC_MAX_COUNT 1
 #define MLXSW_REG_MTBR_LEN (MLXSW_REG_MTBR_BASE_LEN +	\
 			    MLXSW_REG_MTBR_REC_LEN *	\
 			    MLXSW_REG_MTBR_REC_MAX_COUNT)
@@ -9597,12 +9597,12 @@ MLXSW_ITEM32_INDEXED(reg, mtbr, rec_temp, MLXSW_REG_MTBR_BASE_LEN, 0, 16,
 		     MLXSW_REG_MTBR_REC_LEN, 0x00, false);
 
 static inline void mlxsw_reg_mtbr_pack(char *payload, u8 slot_index,
-				       u16 base_sensor_index, u8 num_rec)
+				       u16 base_sensor_index)
 {
 	MLXSW_REG_ZERO(mtbr, payload);
 	mlxsw_reg_mtbr_slot_index_set(payload, slot_index);
 	mlxsw_reg_mtbr_base_sensor_index_set(payload, base_sensor_index);
-	mlxsw_reg_mtbr_num_rec_set(payload, num_rec);
+	mlxsw_reg_mtbr_num_rec_set(payload, 1);
 }
 
 /* Error codes from temperatute reading */