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authorSubrata Banik <subrata.banik@intel.com>2019-04-11 16:34:44 +0530
committerSubrata Banik <subrata.banik@intel.com>2019-04-17 15:05:08 +0000
commit0a9be33a8aa8e41663c58e0f2f1641f44c7cf5de (patch)
tree93e9081bee530feb4b7801f10682fb0dcaa9f257 /src/superio/acpi/pnp_generic.asl
parent26c43b7a77bdf28680ef663ef6eb61f6bf8252ab (diff)
soc/intel/common/timer: Calculate TSC frequency based on CPUID 0x15
This patch ensures to follow Intel SDM Vol 3B Sec 18.7.3 to calculate nominal TSC frequency. As per SDM recommendation: For any processor in which CPUID.15H is enumerated and MSR_PLATFORM_INFO[15:8] (which gives the scalable bus frequency) is available, a more accurate frequency can be obtained by using CPUID.15H This patch also adds header file to capture Intel processor model number. BUG=b:129839774 TEST=Boot ICL platform and calculate TSC frequency using below methods 1. TSC freq calculated based on MSR 0xCE tsc: Detected 1600.000 MHz processor 2. TSC freq calculated based on CPUID 0x15 tsc: Detected 1612.800 MHz TSC Method 2 actually reduce ~25ms of boot performance time. Note: Method 2 is recommended from gen 6 processor onwards. Change-Id: I9ff4b9159a94e61b7e634bd6095f7cc6d7df87c7 Signed-off-by: Subrata Banik <subrata.banik@intel.com> Reviewed-on: https://review.coreboot.org/c/coreboot/+/32283 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Patrick Rudolph <patrick.rudolph@9elements.com> Reviewed-by: Aamir Bohra <aamir.bohra@intel.com>
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