From: "Edward A. James" <eaja...@us.ibm.com>

Pmbus always reads byte data from the status register, even if
configured to use STATUS_WORD. Use a function pointer to read the
correct amount of data from the registers.
Also switch to try STATUS_WORD first before STATUS_BYTE on init.

Signed-off-by: Edward A. James <eaja...@us.ibm.com>
---
 drivers/hwmon/pmbus/pmbus_core.c | 54 +++++++++++++++++++++++++++++-----------
 1 file changed, 40 insertions(+), 14 deletions(-)

diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
index 4ec7586..277d170 100644
--- a/drivers/hwmon/pmbus/pmbus_core.c
+++ b/drivers/hwmon/pmbus/pmbus_core.c
@@ -113,7 +113,8 @@ struct pmbus_data {
         * so we keep them all together.
         */
        u16 status[PB_NUM_STATUS_REG];
-       u8 status_register;
+
+       int (*read_status)(struct i2c_client *client, int page);
 
        u8 currpage;
 };
@@ -324,7 +325,7 @@ static int pmbus_check_status_cml(struct i2c_client *client)
        struct pmbus_data *data = i2c_get_clientdata(client);
        int status, status2;
 
-       status = _pmbus_read_byte_data(client, -1, data->status_register);
+       status = data->read_status(client, -1);
        if (status < 0 || (status & PB_STATUS_CML)) {
                status2 = _pmbus_read_byte_data(client, -1, PMBUS_STATUS_CML);
                if (status2 < 0 || (status2 & PB_CML_FAULT_INVALID_COMMAND))
@@ -348,6 +349,23 @@ static bool pmbus_check_register(struct i2c_client *client,
        return rv >= 0;
 }
 
+static bool pmbus_check_status_register(struct i2c_client *client, int page)
+{
+       int status;
+       struct pmbus_data *data = i2c_get_clientdata(client);
+
+       status = data->read_status(client, page);
+       if (status >= 0 && !(data->flags & PMBUS_SKIP_STATUS_CHECK) &&
+           (status & PB_STATUS_CML)) {
+               status = _pmbus_read_byte_data(client, -1, PMBUS_STATUS_CML);
+               if (status < 0 || (status & PB_CML_FAULT_INVALID_COMMAND))
+                       status = -EIO;
+       }
+
+       pmbus_clear_fault_page(client, -1);
+       return status >= 0;
+}
+
 bool pmbus_check_byte_register(struct i2c_client *client, int page, int reg)
 {
        return pmbus_check_register(client, _pmbus_read_byte_data, page, reg);
@@ -394,8 +412,7 @@ static struct pmbus_data *pmbus_update_device(struct device 
*dev)
 
                for (i = 0; i < info->pages; i++) {
                        data->status[PB_STATUS_BASE + i]
-                           = _pmbus_read_byte_data(client, i,
-                                                   data->status_register);
+                           = data->read_status(client, i);
                        for (j = 0; j < ARRAY_SIZE(pmbus_status); j++) {
                                struct _pmbus_status *s = &pmbus_status[j];
 
@@ -1051,8 +1068,7 @@ static int pmbus_add_sensor_attrs_one(struct i2c_client 
*client,
                 * the generic status register for this page is accessible.
                 */
                if (!ret && attr->gbit &&
-                   pmbus_check_byte_register(client, page,
-                                             data->status_register)) {
+                   pmbus_check_status_register(client, page)) {
                        ret = pmbus_add_boolean(data, name, "alarm", index,
                                                NULL, NULL,
                                                PB_STATUS_BASE + page,
@@ -1729,6 +1745,16 @@ static int pmbus_identify_common(struct i2c_client 
*client,
        return 0;
 }
 
+static int pmbus_read_status_byte(struct i2c_client *client, int page)
+{
+       return _pmbus_read_byte_data(client, page, PMBUS_STATUS_BYTE);
+}
+
+static int pmbus_read_status_word(struct i2c_client *client, int page)
+{
+       return _pmbus_read_word_data(client, page, PMBUS_STATUS_WORD);
+}
+
 static int pmbus_init_common(struct i2c_client *client, struct pmbus_data 
*data,
                             struct pmbus_driver_info *info)
 {
@@ -1736,16 +1762,16 @@ static int pmbus_init_common(struct i2c_client *client, 
struct pmbus_data *data,
        int page, ret;
 
        /*
-        * Some PMBus chips don't support PMBUS_STATUS_BYTE, so try
-        * to use PMBUS_STATUS_WORD instead if that is the case.
+        * Some PMBus chips don't support PMBUS_STATUS_WORD, so try
+        * to use PMBUS_STATUS_BYTE instead if that is the case.
         * Bail out if both registers are not supported.
         */
-       data->status_register = PMBUS_STATUS_BYTE;
-       ret = i2c_smbus_read_byte_data(client, PMBUS_STATUS_BYTE);
-       if (ret < 0 || ret == 0xff) {
-               data->status_register = PMBUS_STATUS_WORD;
-               ret = i2c_smbus_read_word_data(client, PMBUS_STATUS_WORD);
-               if (ret < 0 || ret == 0xffff) {
+       data->read_status = pmbus_read_status_word;
+       ret = i2c_smbus_read_word_data(client, PMBUS_STATUS_WORD);
+       if (ret < 0 || ret == 0xffff) {
+               data->read_status = pmbus_read_status_byte;
+               ret = i2c_smbus_read_byte_data(client, PMBUS_STATUS_BYTE);
+               if (ret < 0 || ret == 0xff) {
                        dev_err(dev, "PMBus status register not found\n");
                        return -ENODEV;
                }
-- 
1.8.3.1

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