fix linux 5.16 freeze regression on 32-bit ThinkPad T40

From: Woody Suwalski <[email protected]>

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 <[email protected]>
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.

Signed-off-by Woody Suwalski <[email protected]>

---

drivers/acpi/processor_idle.c    2022-02-04 14:21:08.264911271 -0500 renamed from drivers/acpi/processor_idle.c    2022-02-04 09:09:54.515906362 -0500 +5 -0

@@ -96,6 +96,11 @@ 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},
      {},
  };
 

Hi,

Quoted 17 lines · Woody Suwalski

From: Woody Suwalski <[email protected]>

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 <[email protected]>
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:

Quoted 7 lines

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.

Signed-off-by Woody Suwalski <[email protected]>

---

Thanks, patch looks good to me:

Reviewed-by Hans de Goede <[email protected]>

Regards,

Hans

drivers/acpi/processor_idle.c 2022-02-04 14:21:08.264911271 -0500 static const struct dmi_system_id proces · line 105

Quoted 13 lines

drivers/acpi/processor_idle.c 2022-02-04 14:21:08.264911271 -0500 renamed from drivers/acpi/processor_idle.c 2022-02-04 09:09:54.515906362 -0500 +5 -0

@@ -96,6 +96,11 @@ 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},
     {},
 };