[PATCH 2/2] hwmon: (pmbus/bpa-rs600) Add workaround for incorrect Pin max

From: Chris Packham
Date: Wed Aug 11 2021 - 00:19:52 EST


BPD-RS600 modules running firmware v5.70 misreport the MFR_PIN_MAX.
The indicate a maximum of 1640W instead of 700W. Detect the invalid
reading and return a sensible value instead.

Signed-off-by: Chris Packham <chris.packham@xxxxxxxxxxxxxxxxxxx>
---
drivers/hwmon/pmbus/bpa-rs600.c | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/drivers/hwmon/pmbus/bpa-rs600.c b/drivers/hwmon/pmbus/bpa-rs600.c
index d495faa89799..f4baed9ce8a4 100644
--- a/drivers/hwmon/pmbus/bpa-rs600.c
+++ b/drivers/hwmon/pmbus/bpa-rs600.c
@@ -65,6 +65,24 @@ static int bpa_rs600_read_vin(struct i2c_client *client)
return ret;
}

+/*
+ * The firmware on some BPD-RS600 models incorrectly reports 1640W
+ * for MFR_PIN_MAX. Deal with this by returning a sensible value.
+ */
+static int bpa_rs600_read_pin_max(struct i2c_client *client)
+{
+ int ret;
+
+ ret = pmbus_read_word_data(client, 0, 0xff, PMBUS_MFR_PIN_MAX);
+ if (ret < 0)
+ return ret;
+
+ if (ret == 0x0b34)
+ return 0x095e;
+
+ return ret;
+}
+
static int bpa_rs600_read_word_data(struct i2c_client *client, int page, int phase, int reg)
{
int ret;
@@ -92,7 +110,8 @@ static int bpa_rs600_read_word_data(struct i2c_client *client, int page, int pha
ret = pmbus_read_word_data(client, 0, 0xff, PMBUS_MFR_IOUT_MAX);
break;
case PMBUS_PIN_OP_WARN_LIMIT:
- ret = pmbus_read_word_data(client, 0, 0xff, PMBUS_MFR_PIN_MAX);
+ case PMBUS_MFR_PIN_MAX:
+ ret = bpa_rs600_read_pin_max(client);
break;
case PMBUS_POUT_OP_WARN_LIMIT:
ret = pmbus_read_word_data(client, 0, 0xff, PMBUS_MFR_POUT_MAX);
--
2.32.0