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hwmon: (pmbus) delta-ahe50dc-fan: work around hardware quirk 

CLEAR_FAULTS commands can apparently sometimes trigger catastrophic
power output glitches on the ahe-50dc, so block them from being sent
at all.

Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20220427035109.3819-1-zev@bewilderbeest.net
Fixes: d387d88ed0 ("hwmon: (pmbus) Add Delta AHE-50DC fan control module driver")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Zev Weiss 2022-04-26 20:51:09 -07:00 committed by Guenter Roeck
parent 75d2b2b06b
commit 08da09f028
1 changed files with 16 additions and 0 deletions
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16
drivers/hwmon/pmbus/delta-ahe50dc-fan.c
View File

@ -14,6 +14,21 @@
#define AHE50DC_PMBUS_READ_TEMP4 0xd0
static int ahe50dc_fan_write_byte(struct i2c_client *client, int page, u8 value)
{
/*
* The CLEAR_FAULTS operation seems to sometimes (unpredictably, perhaps
* 5% of the time or so) trigger a problematic phenomenon in which the
* fan speeds surge momentarily and at least some (perhaps all?) of the
* system's power outputs experience a glitch.
*
* However, according to Delta it should be OK to simply not send any
* CLEAR_FAULTS commands (the device doesn't seem to be capable of
* reporting any faults anyway), so just blackhole them unconditionally.
*/
return value == PMBUS_CLEAR_FAULTS ? -EOPNOTSUPP : -ENODATA;
}
static int ahe50dc_fan_read_word_data(struct i2c_client *client, int page, int phase, int reg)
{
/* temp1 in (virtual) page 1 is remapped to mfr-specific temp4 */
@ -68,6 +83,7 @@ static struct pmbus_driver_info ahe50dc_fan_info = {
PMBUS_HAVE_VIN | PMBUS_HAVE_FAN12 | PMBUS_HAVE_FAN34 |
PMBUS_HAVE_STATUS_FAN12 | PMBUS_HAVE_STATUS_FAN34 | PMBUS_PAGE_VIRTUAL,
.func[1] = PMBUS_HAVE_TEMP | PMBUS_PAGE_VIRTUAL,
.write_byte = ahe50dc_fan_write_byte,
.read_word_data = ahe50dc_fan_read_word_data,
};