From: Patrick Rudolph <patrick.rudolph@xxxxxxxxxxxxx>
After doing performance optimizations the pli1209 driver failed to
probe with a probabilty of 2%. It wasn't able to read the PMBUS_OPERATION
register due to an -EIO error.
An investigation showed that the PLI1209 takes 230 usec to execute the
CLEAR_FAULTS command. During that time it's busy and NACKs all requests
on the SMBUS interface. It also NACKs reads on PMBUS_STATUS_BYTE
making it impossible to poll the BUSY flag.
Add a custom write_data function to just wait for not BUSY unconditionally
after sending a CLEAR_FAULTS command.
TEST: Verified using an I2C bus analyser that no more NACKs are seen after
sending a CLEAR_FAULTS command.
Signed-off-by: Patrick Rudolph <patrick.rudolph@xxxxxxxxxxxxx>
Signed-off-by: Naresh Solanki <Naresh.Solanki@xxxxxxxxxxxxx>
---
drivers/hwmon/pmbus/pli1209bc.c | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/drivers/hwmon/pmbus/pli1209bc.c b/drivers/hwmon/pmbus/pli1209bc.c
index 7d8bd3167b21..c95433790b11 100644
--- a/drivers/hwmon/pmbus/pli1209bc.c
+++ b/drivers/hwmon/pmbus/pli1209bc.c
@@ -5,6 +5,7 @@
* Copyright (c) 2022 9elements GmbH
*/
+#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/pmbus.h>
@@ -53,6 +54,30 @@ static int pli1209bc_read_word_data(struct i2c_client *client, int page,
}
}
+static int pli1209bc_write_byte(struct i2c_client *client, int page, u8 reg)
+{
+ int ret;
+
+ switch (reg) {
+ case PMBUS_CLEAR_FAULTS:
+ ret = pmbus_write_byte(client, page, reg);
+ /*
+ * PLI1209 takes 230 usec to execute the CLEAR_FAULTS command.
+ * During that time it's busy and NACKs all requests on the
+ * SMBUS interface. It also NACKs reads on PMBUS_STATUS_BYTE
+ * making it impossible to poll the BUSY flag.
+ *
+ * Just wait for not BUSY unconditionally.
+ */
+ usleep_range(250, 300);
+ break;
+ default:
+ ret = -ENODATA;
+ break;
+ }
+ return ret;
+}
+
#if IS_ENABLED(CONFIG_SENSORS_PLI1209BC_REGULATOR)
static const struct regulator_desc pli1209bc_reg_desc = {
.name = "vout2",
@@ -102,6 +127,7 @@ static struct pmbus_driver_info pli1209bc_info = {
| PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP
| PMBUS_HAVE_STATUS_IOUT | PMBUS_HAVE_STATUS_INPUT,
.read_word_data = pli1209bc_read_word_data,
+ .write_byte = pli1209bc_write_byte,
#if IS_ENABLED(CONFIG_SENSORS_PLI1209BC_REGULATOR)
.num_regulators = 1,
.reg_desc = &pli1209bc_reg_desc,
--
2.41.0
