linux-kernel - [PATCH 2/4] platform: arm64: thinkpad-t14s-ec: sleep after EC access

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20251106-thinkpad-t14s-ec-improvements-v1-2-109548ae75c0@collabora.com>
Date: Thu, 06 Nov 2025 00:22:41 +0100
From: Sebastian Reichel <sre@...nel.org>
To: Sebastian Reichel <sre@...nel.org>, Hans de Goede <hansg@...nel.org>, 
 Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>, 
 Bryan O'Donoghue <bryan.odonoghue@...aro.org>
Cc: platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/4] platform: arm64: thinkpad-t14s-ec: sleep after EC
 access

The ACPI ECRD and ECWR functions have a 10ms sleep at the end. It turns
out, that this is sometimes needed to avoid I2C transmission failures,
especially for functions doing regmap_update_bits (and thus read + write
shortly after each other). This fixes problems like the following
appearing in the kernel log:

leds platform::micmute: Setting an LED's brightness failed (-6)
leds platform::kbd_backlight: Setting an LED's brightness failed (-6)

The ACPI QEVT function used to read the interrupt status register also
has a 10ms sleep at the end. Without that there are problems with
reading multiple events following directly after each other resulting
in the following error message being logged:

thinkpad-t14s-ec 4-0028: Failed to read event

Fixes: 60b7ab6ce030 ("platform: arm64: thinkpad-t14s-ec: new driver")
Signed-off-by: Sebastian Reichel <sre@...nel.org>
---
 drivers/platform/arm64/lenovo-thinkpad-t14s.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/platform/arm64/lenovo-thinkpad-t14s.c b/drivers/platform/arm64/lenovo-thinkpad-t14s.c
index c1c01b977f2b..cf6a1d3b2617 100644
--- a/drivers/platform/arm64/lenovo-thinkpad-t14s.c
+++ b/drivers/platform/arm64/lenovo-thinkpad-t14s.c
@@ -120,6 +120,7 @@ static int t14s_ec_write(void *context, unsigned int reg,
 	if (ret < 0)
 		return ret;
 
+	fsleep(10000);
 	return 0;
 }
 
@@ -157,6 +158,7 @@ static int t14s_ec_read(void *context, unsigned int reg,
 
 out:
 	i2c_unlock_bus(client->adapter, I2C_LOCK_SEGMENT);
+	fsleep(10000);
 	return ret;
 }
 
@@ -191,6 +193,8 @@ static int t14s_ec_read_evt(struct t14s_ec *ec, u8 *val)
 	if (ret < 0)
 		goto out;
 
+	fsleep(10000);
+
 	ret = 0;
 
 out:

-- 
2.51.0