It's a oneliner and the patch is from linus' tree.
---
in commit eaa7571b2d1a08873e4bdd8e6db3431df61cd9ad, a safety net for TPEC
fan control mode was added. Quoting that patch:
"The Linux ThinkPad community is not positive that all ThinkPads that do
HFSP EC fan control do implement full-speed and auto modes, some of the
earlier ones supporting HFSP might not.
If the EC ignores the AUTO or FULL-SPEED bits, it will pay attention to the
lower three bits that set the fan level. And as thinkpad-acpi was leaving
these set to zero, it would stop(!) the fan, which is Not A Good Thing.
So, as a safety net, we now make sure to also set the fan level part of the
HFSP register to speed 7 for full-speed, and a minimum of speed 4 for auto
mode."
However, in the section below the test for the FULL-SPEED bits was not added:
the AUTO bits were tested twice. This patch corrects this and ensures that
the fan level part of the HFSP register is set to a minimum of speed 4 for
auto mode.
Signed-off-by: Roel Kluin <12o3l@tiscali.nl>
---
diff --git a/drivers/misc/thinkpad_acpi.c b/drivers/misc/thinkpad_acpi.c
index cf56647..3c323fe 100644
--- a/drivers/misc/thinkpad_acpi.c
+++ b/drivers/misc/thinkpad_acpi.c
@@ -4138,7 +4138,7 @@ static int fan_set_level(int level)
* or FULLSPEED mode bits and just ignore them */
if (level & TP_EC_FAN_FULLSPEED)
level |= 7; /* safety min speed 7 */
- else if (level & TP_EC_FAN_FULLSPEED)
+ else if (level & TP_EC_FAN_AUTO)
level |= 4; /* safety min speed 4 */
if (!acpi_ec_write(fan_status_offset, level))
--
