7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Vishnu Razdan commit 6d760f8b41aed74de4402440e4db663d261478bd upstream. Some hwmon alarms fall back to STATUS_WORD summary bits when no individual limit alarm is available. On PMBus 1.2 and newer devices, pmbus_get_boolean() acknowledges these alarms with the same byte-data write used for detailed status registers. For example, PB_STATUS_INPUT is 0x2000, so it is truncated to zero when passed to _pmbus_write_byte_data(). The resulting write cannot acknowledge the input alarm. PMBus 1.3 Part II, sections 10.2.4 and 10.2.5, excludes ordinary STATUS_BYTE and STATUS_WORD summary bits from individual clearing. Their summary bits clear when the underlying status bits clear, so changing this to a word-data write would not fix the generic input alarm either. Use the existing page CLEAR_FAULTS path for generic STATUS_WORD alarms, including devices whose status accessor uses STATUS_BYTE. Keep individual byte writes for detailed status registers on PMBus 1.2 and newer devices. As with the existing older-device fallback, CLEAR_FAULTS can clear other latched status; an active condition can reassert its status. Fixes: 35f165f08950 ("hwmon: (pmbus) Clear pmbus fault/warning bits after read") Cc: stable@vger.kernel.org Assisted-by: LLM Signed-off-by: Vishnu Razdan Link: https://patch.msgid.link/20260824-vrazdan-pmbus-status-word-b4-v1-1-2606ecd0c029@openai.com Signed-off-by: Guenter Roeck Signed-off-by: Greg Kroah-Hartman --- drivers/hwmon/pmbus/pmbus_core.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/drivers/hwmon/pmbus/pmbus_core.c +++ b/drivers/hwmon/pmbus/pmbus_core.c @@ -1192,7 +1192,9 @@ static int pmbus_get_boolean(struct i2c_ regval = status & mask; if (regval) { - if (data->revision >= PMBUS_REV_12) { + /* Generic STATUS_WORD alarms are not individually clearable. */ + if (data->revision >= PMBUS_REV_12 && + reg != PMBUS_STATUS_WORD) { ret = _pmbus_write_byte_data(client, page, reg, regval); if (ret) return ret;