[ltp] (fwd) [PATCH] Enable bit 11 in _PDC to advertise hw coord
Henrique de Moraes Holschuh
linux-thinkpad@linux-thinkpad.org
Sun, 8 Feb 2009 10:14:35 -0200
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This patch is known to help reduce overhead on the X60, and it is
probably usefull for all Lenovo Laptops, and maybe even on the IBM
ones...
It will be in one of the next stable kernel updates, but here it is in
advance for anyone that wants to add it early to their kernels...
--
"One disk to rule them all, One disk to find them. One disk to bring
them all and in the darkness grind them. In the Land of Redmond
where the shadows lie." -- The Silicon Valley Tarot
Henrique Holschuh
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Date: Mon, 2 Feb 2009 11:57:18 -0800
From: "Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>
To: Len Brown <lenb@kernel.org>
Cc: linux-acpi@vger.kernel.org, Jens Axboe <jens.axboe@oracle.com>,
Chris Mason <chris.mason@oracle.com>
Subject: [PATCH] Enable bit 11 in _PDC to advertise hw coord
Message-ID: <20090202195717.GA24510@linux-os.sc.intel.com>
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Bit 11 in intel PDC definitions is meant for OS capability to handle
hardware coordination of P-states. In Linux we have always supported
hwardware coordination of P-states. Just let the BIOSes know that we
support it, by setting this bit.
Some BIOSes use this bit to choose between hardware or software coordination
and without this change below, BIOSes switch to software coordination, which
is not very optimal in terms of power consumption and extra wakeups from idle.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
---
include/acpi/pdc_intel.h | 2 ++
1 file changed, 2 insertions(+)
Index: linux-2.6/include/acpi/pdc_intel.h
===================================================================
--- linux-2.6.orig/include/acpi/pdc_intel.h 2009-01-20 16:11:20.000000000 -0800
+++ linux-2.6/include/acpi/pdc_intel.h 2009-02-02 10:32:06.000000000 -0800
@@ -14,6 +14,7 @@
#define ACPI_PDC_SMP_T_SWCOORD (0x0080)
#define ACPI_PDC_C_C1_FFH (0x0100)
#define ACPI_PDC_C_C2C3_FFH (0x0200)
+#define ACPI_PDC_SMP_P_HWCOORD (0x0800)
#define ACPI_PDC_EST_CAPABILITY_SMP (ACPI_PDC_SMP_C1PT | \
ACPI_PDC_C_C1_HALT | \
@@ -22,6 +23,7 @@
#define ACPI_PDC_EST_CAPABILITY_SWSMP (ACPI_PDC_SMP_C1PT | \
ACPI_PDC_C_C1_HALT | \
ACPI_PDC_SMP_P_SWCOORD | \
+ ACPI_PDC_SMP_P_HWCOORD | \
ACPI_PDC_P_FFH)
#define ACPI_PDC_C_CAPABILITY_SMP (ACPI_PDC_SMP_C2C3 | \
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