6.6-stable review patch. If anyone has any objections, please let me know.
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From: Rong Zhang i@rong.moe
[ Upstream commit 5808c34216954cd832bd4b8bc52dfa287049122b ]
It was reported that ideapad-laptop sometimes causes some recent (since 2024) Lenovo ThinkBook models shut down when: - suspending/resuming - closing/opening the lid - (dis)connecting a charger - reading/writing some sysfs properties, e.g., fan_mode, touchpad - pressing down some Fn keys, e.g., Brightness Up/Down (Fn+F5/F6) - (seldom) loading the kmod
The issue has existed since the launch day of such models, and there have been some out-of-tree workarounds (see Link:) for the issue. One disables some functionalities, while another one simply shortens IDEAPAD_EC_TIMEOUT. The disabled functionalities have read_ec_data() in their call chains, which calls schedule() between each poll.
It turns out that these models suffer from the indeterminacy of schedule() because of their low tolerance for being polled too frequently. Sometimes schedule() returns too soon due to the lack of ready tasks, causing the margin between two polls to be too short. In this case, the command is somehow aborted, and too many subsequent polls (they poll for "nothing!") may eventually break the state machine in the EC, resulting in a hard shutdown. This explains why shortening IDEAPAD_EC_TIMEOUT works around the issue - it reduces the total number of polls sent to the EC.
Even when it doesn't lead to a shutdown, frequent polls may also disturb the ongoing operation and notably delay (+ 10-20ms) the availability of EC response. This phenomenon is unlikely to be exclusive to the models mentioned above, so dropping the schedule() manner should also slightly improve the responsiveness of various models.
Fix these issues by migrating to usleep_range(150, 300). The interval is chosen to add some margin to the minimal 50us and considering EC responses are usually available after 150-2500us based on my test. It should be enough to fix these issues on all models subject to the EC bug without introducing latency on other models.
Tested on ThinkBook 14 G7+ ASP and solved both issues. No regression was introduced in the test on a model without the EC bug (ThinkBook X IMH, thanks Eric).
Link: https://github.com/ty2/ideapad-laptop-tb2024g6plus/commit/6c5db18c9e8109873c... Link: https://github.com/ferstar/ideapad-laptop-tb/commit/42d1e68e5009529d31bd23f9... Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218771 Fixes: 6a09f21dd1e2 ("ideapad: add ACPI helpers") Cc: stable@vger.kernel.org Tested-by: Felix Yan felixonmars@archlinux.org Tested-by: Eric Long i@hack3r.moe Tested-by: Jianfei Zhang zhangjianfei3@gmail.com Tested-by: Mingcong Bai jeffbai@aosc.io Tested-by: Minh Le minhld139@gmail.com Tested-by: Sicheng Zhu Emmet_Z@outlook.com Signed-off-by: Rong Zhang i@rong.moe Link: https://lore.kernel.org/r/20250525201833.37939-1-i@rong.moe Reviewed-by: Ilpo Järvinen ilpo.jarvinen@linux.intel.com Signed-off-by: Ilpo Järvinen ilpo.jarvinen@linux.intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/platform/x86/ideapad-laptop.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-)
diff --git a/drivers/platform/x86/ideapad-laptop.c b/drivers/platform/x86/ideapad-laptop.c index db8256cde34aa..e84fcb444d872 100644 --- a/drivers/platform/x86/ideapad-laptop.c +++ b/drivers/platform/x86/ideapad-laptop.c @@ -14,6 +14,7 @@ #include <linux/bitops.h> #include <linux/bug.h> #include <linux/debugfs.h> +#include <linux/delay.h> #include <linux/device.h> #include <linux/dmi.h> #include <linux/fb.h> @@ -265,6 +266,20 @@ static void ideapad_shared_exit(struct ideapad_private *priv) */ #define IDEAPAD_EC_TIMEOUT 200 /* in ms */
+/* + * Some models (e.g., ThinkBook since 2024) have a low tolerance for being + * polled too frequently. Doing so may break the state machine in the EC, + * resulting in a hard shutdown. + * + * It is also observed that frequent polls may disturb the ongoing operation + * and notably delay the availability of EC response. + * + * These values are used as the delay before the first poll and the interval + * between subsequent polls to solve the above issues. + */ +#define IDEAPAD_EC_POLL_MIN_US 150 +#define IDEAPAD_EC_POLL_MAX_US 300 + static int eval_int(acpi_handle handle, const char *name, unsigned long *res) { unsigned long long result; @@ -381,7 +396,7 @@ static int read_ec_data(acpi_handle handle, unsigned long cmd, unsigned long *da end_jiffies = jiffies + msecs_to_jiffies(IDEAPAD_EC_TIMEOUT) + 1;
while (time_before(jiffies, end_jiffies)) { - schedule(); + usleep_range(IDEAPAD_EC_POLL_MIN_US, IDEAPAD_EC_POLL_MAX_US);
err = eval_vpcr(handle, 1, &val); if (err) @@ -412,7 +427,7 @@ static int write_ec_cmd(acpi_handle handle, unsigned long cmd, unsigned long dat end_jiffies = jiffies + msecs_to_jiffies(IDEAPAD_EC_TIMEOUT) + 1;
while (time_before(jiffies, end_jiffies)) { - schedule(); + usleep_range(IDEAPAD_EC_POLL_MIN_US, IDEAPAD_EC_POLL_MAX_US);
err = eval_vpcr(handle, 1, &val); if (err)