Fw: Followup on 2.6.13-rc3 ACPI processor C-state regression

[Andrew Morton <akpm-3NddpPZAyC0@public.gmane.org>]

There's another regression being reported over on lkml.

Begin forwarded message:

Date: Wed, 13 Jul 2005 18:05:30 -0400
From: Kevin Radloff <radsaq-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Followup on 2.6.13-rc3 ACPI processor C-state regression


Previously, I had said that in 2.6.13-rc3, C2/C3 capabilities were not
detected on my Fujitsu Lifebook P7010D. I found that in the merge at:

http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blobdiff;h=893b074e3d1a48a4390cf84b4c1a10ef6be2460c;hp=c9d671cf7857dbc7101e99d469fa24eed711ac60;hb=5028770a42e7bc4d15791a44c28f0ad539323807;f=drivers/acpi/processor_idle.c

.. in the section at (please forgive my destruction of the formatting) ...

@@ -787,10 +843,7 @@ static int acpi_processor_get_power_info
         if ((result) || (acpi_processor_power_verify(pr) < 2)) {
             result = acpi_processor_get_power_info_fadt(pr);
             if (result)
-                return_VALUE(result);
-
-            if (acpi_processor_power_verify(pr) < 2)
-                return_VALUE(-ENODEV);
+               result = acpi_processor_get_power_info_default_c1(pr);
         }

.. a call to acpi_processor_power_verify() is removed, which breaks
detection of C2/C3 capabilities if the above
acpi_processor_get_power_info_cst() failed. It it had succeeded (and
returned 0), then acpi_processor_power_verify() is called in the
conditional statement, which will set the valid flags for C2/C3. But
if it fails, like on my laptop, then the valid flags will never be
set, despite the fact that the acpi_processor_get_power_info_fadt()
function finds the necessary info for a subsequent
acpi_processor_power_verify() call to succeed.

I don't know what exactly the proper fix here is (with the
introduction of the acpi_processor_get_power_info_default_c1()
function, that is), but simply reversing this part of the patch fixes
detection of C2/C3 on my laptop.

Please CC me with any followups, as I'm not on the list.

-- 
Kevin 'radsaq' Radloff
radsaq-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
http://saqataq.us/
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