From: Daniel Salmun <salmundani@gmail.com>
To: "Henrique de Moraes Holschuh" <hmh@hmh.eng.br>,
"Mark Pearson" <mpearson-lenovo@squebb.ca>,
"Derek J . Clark" <derekjohn.clark@gmail.com>,
"Hans de Goede" <hansg@kernel.org>,
"Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>
Cc: ibm-acpi-devel@lists.sourceforge.net,
platform-driver-x86@vger.kernel.org,
linux-kernel@vger.kernel.org,
Daniel Salmun <salmundani@gmail.com>
Subject: [PATCH] platform/x86: thinkpad_acpi: Fix fan speed reporting on ThinkPad L440
Date: Mon, 14 Sep 2026 23:05:03 -0300 [thread overview]
Message-ID: <20260915020503.18987-1-salmundani@gmail.com> (raw)
The L440 (BIOS J4ET93WW) reports its fan as stopped: /proc/acpi/ibm/fan
shows "status: disabled" and "speed: 0", and hwmon fan1_input is 0 under
any load. EC registers 0x2F and 0x84/0x85 always read 0 on this model.
The EC uses the 0x93/0x95 layout handled by TPACPI_FAN_NS. 0x93 reads 4
(FAN_NS_CTRL_STATUS) and 0x95 goes from 255 at idle to about 111 at full
speed. The DSDT has no fan methods.
Add model ID "J4" to fan_quirk_table. The fan then reads about 1900 RPM
at idle and 2900 RPM under load.
Tested on a ThinkPad L440 20ASS20200 with BIOS J4ET93WW and EC J4HT30WW.
Link: https://github.com/lm-sensors/lm-sensors/issues/510
Signed-off-by: Daniel Salmun <salmundani@gmail.com>
---
Manual fan control works on this EC (0x93 = 0x14, target written to
0x94) but is not part of this patch.
I have not checked FAN_RPM_CAL_CONST against a real tachometer. With it
the range is 1927-4428 RPM, which fits the 5 V blower in this machine.
The L540 uses the same EC firmware and probably needs the same entry,
but I don't have one to check its model ID.
drivers/platform/x86/lenovo/thinkpad_acpi.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/platform/x86/lenovo/thinkpad_acpi.c b/drivers/platform/x86/lenovo/thinkpad_acpi.c
index 1661f070c..c63e54eaa 100644
--- a/drivers/platform/x86/lenovo/thinkpad_acpi.c
+++ b/drivers/platform/x86/lenovo/thinkpad_acpi.c
@@ -8846,6 +8846,7 @@ static const struct tpacpi_quirk fan_quirk_table[] __initconst = {
TPACPI_Q_LNV3('R', '1', 'D', TPACPI_FAN_NS), /* 11e Gen5 GL-R */
TPACPI_Q_LNV3('R', '0', 'V', TPACPI_FAN_NS), /* 11e Gen5 KL-Y */
TPACPI_Q_LNV('H', '3', TPACPI_FAN_NS), /* Edge E330 */
+ TPACPI_Q_LNV('J', '4', TPACPI_FAN_NS), /* L440 */
TPACPI_Q_LNV3('N', '1', 'O', TPACPI_FAN_NOFAN), /* X1 Tablet (2nd gen) */
TPACPI_Q_LNV3('R', '0', 'Q', TPACPI_FAN_DECRPM),/* L480 */
TPACPI_Q_LNV('8', 'F', TPACPI_FAN_TPR), /* ThinkPad x120e */
base-commit: cee9395acd8043be0644b25c34bfa86623f2b935
--
2.34.1
reply other threads:[~2026-09-15 2:05 UTC|newest]
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