The core cpufreq code doesn't appear to understand returning -EAGAIN
for the get() function of the cpufreq_driver. If PAL_GET_PSTATE returns
-1, such as when running on Xen, scaling_cur_freq is happy to return
4294967285 kHz (ie. (unsigned)-11). The other drivers appear to return
0 for a failure, and doing so gives me the max frequency from
scaling_cur_frequency and "<unknown>" from cpuinfo_cur_frequency. I
believe that's the desired behavior.
Signed-off-by: Alex Williamson <alex.williamson@hp.com>
Acked-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
PAL_GET_PSTATE accepts a type argument to return different kinds of
frequency information.
Refer: Intel Itanium®Architecture Software Developer's Manual -
Volume 2: System Architecture, Revision 2.2
(http://developer.intel.com/design/itanium/manuals/245318.htm)
Add the support for type argument and use Instantaneous frequency
in the acpi driver.
Also fix a bug, where in return value of PAL_GET_PSTATE was getting compared
with 'control' bits instead of 'status' bits.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Linux invokes the AML _PDC method (Processor Driver Capabilities)
to tell the BIOS what features it can handle. While the ACPI
spec says nothing about the OS invoking _PDC multiple times,
doing so with changing bits seems to hopelessly confuse the BIOS
on multiple platforms up to and including crashing the system.
Factor out the _PDC invocation so Linux invokes it only once.
http://bugzilla.kernel.org/show_bug.cgi?id=5483
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Patch to support P-state transitions on ia64. This driver is based on ACPI,
and uses the ACPI processor driver interface to find out the P-state support
information for the processor. This driver plugs into generic cpufreq
infrastructure.
Once this driver is loaded successfully, ondemand/userspace governor can be
used to change the CPU frequency dynamically based on load or on request from
userspace process.
Refer :
ACPI specification -
http://www.acpi.info
P-state related PAL calls -
http://developer.intel.com/design/itanium/downloads/24869909.pdf
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Otherwise a platform that supports ACPI based cpufreq
and boots up at lowest possible speed could stay there
forever. This because the governor may request max speed,
but the code doesn't update if there is no change in
speed, and it assumed the initial state of max speed.
http://bugzilla.kernel.org/show_bug.cgi?id=4634
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Alex Williamson