The commit 1feb31e810b0 ("hwmon: (pmbus/mp2975) Simplify VOUT code")
has introduced a bug that makes it impossible to initialize MP2975
device:
"""
mp2975 5-0020: Failed to identify chip capabilities
i2c i2c-5: new_device: Instantiated device mp2975 at 0x20
i2c i2c-5: delete_device: Deleting device mp2975 at 0x20
"""
Since the 'read_byte_data' function was removed from the
'pmbus_driver_info ' structure the driver no longer reports correctly
that VOUT mode is direct. Therefore 'pmbus_identify_common' fails
with error, making it impossible to initialize the device.
Restore 'read_byte_data' function to fix the issue.
Tested:
- before: it is not possible to initialize MP2975 device with the
'mp2975' driver,
- after: 'mp2975' correctly initializes MP2975 device and all sensor
data is correct.
Fixes: 1feb31e810b0 ("hwmon: (pmbus/mp2975) Simplify VOUT code")
Signed-off-by: Konstantin Aladyshev <aladyshev22@xxxxxxxxx>
---
Changes in v4:
- Correct comment inside the 'mp2975_read_byte_data' function as
suggested by Patrick Rudolph
Changes in v3:
- Drop accidentally added file from patch
Changes in v2:
- Fix indentation issues
drivers/hwmon/pmbus/mp2975.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/drivers/hwmon/pmbus/mp2975.c b/drivers/hwmon/pmbus/mp2975.c
index b9bb469e2d8f..e5fa10b3b8bc 100644
--- a/drivers/hwmon/pmbus/mp2975.c
+++ b/drivers/hwmon/pmbus/mp2975.c
@@ -126,6 +126,21 @@ static const struct regulator_desc __maybe_unused mp2975_reg_desc[] = {
#define to_mp2975_data(x) container_of(x, struct mp2975_data, info)
+static int mp2975_read_byte_data(struct i2c_client *client, int page, int reg)
+{
+ switch (reg) {
+ case PMBUS_VOUT_MODE:
+ /*
+ * Report direct format as configured by MFR_DC_LOOP_CTRL.
+ * Unlike on MP2971/MP2973 the reported VOUT_MODE isn't automatically
+ * internally updated, but always reads as PB_VOUT_MODE_VID.
+ */
+ return PB_VOUT_MODE_DIRECT;
+ default:
+ return -ENODATA;
+ }
+}
+
static int
mp2975_read_word_helper(struct i2c_client *client, int page, int phase, u8 reg,
u16 mask)
@@ -869,6 +884,7 @@ static struct pmbus_driver_info mp2975_info = {
PMBUS_HAVE_IIN | PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT |
PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP | PMBUS_HAVE_POUT |
PMBUS_HAVE_PIN | PMBUS_HAVE_STATUS_INPUT | PMBUS_PHASE_VIRTUAL,
+ .read_byte_data = mp2975_read_byte_data,
.read_word_data = mp2975_read_word_data,
#if IS_ENABLED(CONFIG_SENSORS_MP2975_REGULATOR)
.num_regulators = 1,
--
2.34.1
