From: Woody Suwalski wsuwalski@gmail.com
commit bfe55a1f7fd6bfede16078bf04c6250fbca11588 upstream.
Add and ACPI idle power level limit for 32-bit ThinkPad T40.
There is a regression on T40 introduced by commit d6b88ce2, starting with kernel 5.16:
commit d6b88ce2eb9d2698eb24451eb92c0a1649b17bb1 Author: Richard Gong richard.gong@amd.com Date: Wed Sep 22 08:31:16 2021 -0500
ACPI: processor idle: Allow playing dead in C3 state
The above patch is trying to enter C3 state during init, what is causing a T40 system freeze. I have not found a similar issue on any other of my 32-bit machines.
The fix is to add another exception to the processor_power_dmi_table[] list. As a result the dmesg shows as expected:
[2.155398] ACPI: IBM ThinkPad T40 detected - limiting to C2 max_cstate. Override with "processor.max_cstate=9" [2.155404] ACPI: processor limited to max C-state 2
The fix is trivial and affects only vintage T40 systems.
Fixes: d6b88ce2eb9d ("CPI: processor idle: Allow playing dead in C3 state") Signed-off-by: Woody Suwalski wsuwalski@gmail.com Reviewed-by: Hans de Goede hdegoede@redhat.com Cc: 5.16+ stable@vger.kernel.org # 5.16+ [ rjw: New subject ] Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/acpi/processor_idle.c | 5 +++++ 1 file changed, 5 insertions(+)
--- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -95,6 +95,11 @@ static const struct dmi_system_id proces DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK Computer Inc."), DMI_MATCH(DMI_PRODUCT_NAME,"L8400B series Notebook PC")}, (void *)1}, + /* T40 can not handle C3 idle state */ + { set_max_cstate, "IBM ThinkPad T40", { + DMI_MATCH(DMI_SYS_VENDOR, "IBM"), + DMI_MATCH(DMI_PRODUCT_NAME, "23737CU")}, + (void *)2}, {}, };