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From: Jan Pogadl <pogadl.jan@googlemail.com>
To: linux-acpi@vger.kernel.org
Cc: achiang@hp.com
Subject: [BUG, REGRESSION] ACPI: Set _PDC
Date: Thu, 17 Jun 2010 00:40:24 +0200	[thread overview]
Message-ID: <201006170040.24736.pogadl.jan@googlemail.com> (raw)

Hi,

with commit commit 5d554a7bb0643a6151a84319bfeba8270bf5269e (ACPI: processor: 
add internal processor_physically_present()) a new function got introduced which 
always fails on machines with CONFIG_SMP disabled. Thus _PDC will never be 
initialized? set?. 

The problem of the processor_physically_present() is, that it calls the 
acpi_get_cpuid(...) function which returns on NON-SMP machines always -1.

Note that i don't have any real knowledge what _PDC actualy realy do, all i 
gatherd so far is that its for switching C-Stats. I Stumbled across this by 
bisecting the problem, that the undervolting patches from
linux-phc.org aren't working anymore with 2.6.34 (2.6.35-rc3). Whereas they 
worked fine with 2.6.33 on my  Samsung X20 Notebook with a Pentium M precossor. 
The acpi-cpufreq is now using System-IO instead of MSR Registers. 

Since i don't know what should be the correct behaviour here i can't
provide any patches. But i doub't it's the correct behaviour of 
processor_physically_present() to always fail on non-SMP machines. 
 
Deleting the function call, to this new function in early_init_pdc(...), 
and i get back the old behaviour.

cheers,
jan

             reply	other threads:[~2010-06-16 22:40 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-06-16 22:40 Jan Pogadl [this message]
2010-06-17  3:24 ` [BUG, REGRESSION] ACPI: Set _PDC Alex Chiang
2010-06-17  7:51   ` Jan Pogadl
2010-06-17  7:56     ` Chen Gong
2010-06-17 14:54       ` Alex Chiang

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