diff options
author | Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> | 2005-10-23 20:31:00 (GMT) |
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committer | Len Brown <len.brown@intel.com> | 2005-12-01 06:30:35 (GMT) |
commit | 05131ecc99ea9da7f45ba3058fe8a2c1d0ceeab8 (patch) | |
tree | dec76975406874cf677d6391302f42a6da55ac38 /arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c | |
parent | d2149b542382bfc206cb28485108f6470c979566 (diff) | |
download | linux-fsl-qoriq-05131ecc99ea9da7f45ba3058fe8a2c1d0ceeab8.tar.xz |
[ACPI] Avoid BIOS inflicted crashes by evaluating _PDC only once
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>
Diffstat (limited to 'arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c')
-rw-r--r-- | arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c | 67 |
1 files changed, 0 insertions, 67 deletions
diff --git a/arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c b/arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c index 871366b..31ce890 100644 --- a/arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c +++ b/arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c @@ -297,68 +297,6 @@ acpi_cpufreq_guess_freq ( } -/* - * acpi_processor_cpu_init_pdc_est - let BIOS know about the SMP capabilities - * of this driver - * @perf: processor-specific acpi_io_data struct - * @cpu: CPU being initialized - * - * To avoid issues with legacy OSes, some BIOSes require to be informed of - * the SMP capabilities of OS P-state driver. Here we set the bits in _PDC - * accordingly, for Enhanced Speedstep. Actual call to _PDC is done in - * driver/acpi/processor.c - */ -static void -acpi_processor_cpu_init_pdc_est( - struct acpi_processor_performance *perf, - unsigned int cpu, - struct acpi_object_list *obj_list - ) -{ - union acpi_object *obj; - u32 *buf; - struct cpuinfo_x86 *c = cpu_data + cpu; - dprintk("acpi_processor_cpu_init_pdc_est\n"); - - if (!cpu_has(c, X86_FEATURE_EST)) - return; - - /* Initialize pdc. It will be used later. */ - if (!obj_list) - return; - - if (!(obj_list->count && obj_list->pointer)) - return; - - obj = obj_list->pointer; - if ((obj->buffer.length == 12) && obj->buffer.pointer) { - buf = (u32 *)obj->buffer.pointer; - buf[0] = ACPI_PDC_REVISION_ID; - buf[1] = 1; - buf[2] = ACPI_PDC_EST_CAPABILITY_SMP; - perf->pdc = obj_list; - } - return; -} - - -/* CPU specific PDC initialization */ -static void -acpi_processor_cpu_init_pdc( - struct acpi_processor_performance *perf, - unsigned int cpu, - struct acpi_object_list *obj_list - ) -{ - struct cpuinfo_x86 *c = cpu_data + cpu; - dprintk("acpi_processor_cpu_init_pdc\n"); - perf->pdc = NULL; - if (cpu_has(c, X86_FEATURE_EST)) - acpi_processor_cpu_init_pdc_est(perf, cpu, obj_list); - return; -} - - static int acpi_cpufreq_cpu_init ( struct cpufreq_policy *policy) @@ -373,9 +311,6 @@ acpi_cpufreq_cpu_init ( struct acpi_object_list arg_list = {1, &arg0}; dprintk("acpi_cpufreq_cpu_init\n"); - /* setup arg_list for _PDC settings */ - arg0.buffer.length = 12; - arg0.buffer.pointer = (u8 *) arg0_buf; data = kzalloc(sizeof(struct cpufreq_acpi_io), GFP_KERNEL); if (!data) @@ -383,9 +318,7 @@ acpi_cpufreq_cpu_init ( acpi_io_data[cpu] = data; - acpi_processor_cpu_init_pdc(&data->acpi_data, cpu, &arg_list); result = acpi_processor_register_performance(&data->acpi_data, cpu); - data->acpi_data.pdc = NULL; if (result) goto err_free; |