[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>
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Len Brown
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d2149b5423
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05131ecc99
@ -253,31 +253,21 @@ static int acpi_processor_errata(struct acpi_processor *pr)
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* _PDC is required for a BIOS-OS handshake for most of the newer
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* ACPI processor features.
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*/
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int acpi_processor_set_pdc(struct acpi_processor *pr,
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struct acpi_object_list *pdc_in)
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static int acpi_processor_set_pdc(struct acpi_processor *pr)
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{
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struct acpi_object_list *pdc_in = pr->pdc;
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acpi_status status = AE_OK;
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u32 arg0_buf[3];
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union acpi_object arg0 = { ACPI_TYPE_BUFFER };
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struct acpi_object_list no_object = { 1, &arg0 };
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struct acpi_object_list *pdc;
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ACPI_FUNCTION_TRACE("acpi_processor_set_pdc");
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arg0.buffer.length = 12;
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arg0.buffer.pointer = (u8 *) arg0_buf;
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arg0_buf[0] = ACPI_PDC_REVISION_ID;
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arg0_buf[1] = 0;
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arg0_buf[2] = 0;
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if (!pdc_in)
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return_VALUE(status);
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pdc = (pdc_in) ? pdc_in : &no_object;
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status = acpi_evaluate_object(pr->handle, "_PDC", pdc_in, NULL);
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status = acpi_evaluate_object(pr->handle, "_PDC", pdc, NULL);
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if ((ACPI_FAILURE(status)) && (pdc_in))
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if (ACPI_FAILURE(status))
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ACPI_DEBUG_PRINT((ACPI_DB_INFO,
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"Error evaluating _PDC, using legacy perf. control...\n"));
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"Could not evaluate _PDC, using legacy perf. control...\n"));
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return_VALUE(status);
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}
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@ -574,6 +564,10 @@ static int acpi_processor_start(struct acpi_device *device)
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"Error installing device notify handler\n"));
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}
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/* _PDC call should be done before doing anything else (if reqd.). */
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arch_acpi_processor_init_pdc(pr);
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acpi_processor_set_pdc(pr);
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acpi_processor_power_init(pr, device);
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if (pr->flags.throttling) {
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