From e7593bda6a2e2e46521567f0ddea940f4acda0db Mon Sep 17 00:00:00 2001 From: Patrick Rudolph Date: Thu, 17 Aug 2023 11:25:26 +0200 Subject: hwmon: pmbus: Fix -EIO seen on pli1209 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 Signed-off-by: Naresh Solanki Link: https://lore.kernel.org/r/20230817092527.808631-3-Naresh.Solanki@9elements.com Signed-off-by: Guenter Roeck --- drivers/hwmon/pmbus/pli1209bc.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) (limited to 'drivers') 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 #include #include #include @@ -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, -- cgit v1.2.3