On AMD Ryzen Embedded V1780B (Family 17h, Zen 1), the BIOS does not provide ACPI _CPC objects and the CPU does not support MSR-based CPPC (X86_FEATURE_CPPC). The _PSS table only lists nominal P-states (P0 = 3350 MHz), so when get_max_boost_ratio() fails at cppc_get_perf_caps(), cpuinfo_max_freq reports only the base frequency instead of the rated boost frequency (3600 MHz). dmesg: ACPI CPPC: No CPC descriptor for CPU:0 acpi_cpufreq: CPU0: Unable to get performance capabilities (-19) cppc-cpufreq already has a DMI fallback (cppc_get_dmi_max_khz()) that reads the processor max speed from SMBIOS Type 4. Export it and reuse it in acpi-cpufreq as a last-resort source for the boost frequency. A sanity check ensures the DMI value is above the _PSS P0 frequency and within 2x of it; values outside that range are ignored and the existing arch_set_max_freq_ratio() path is taken instead. The 2x upper bound is based on a survey of the AMD Ryzen Embedded V1000 series, where the highest boost-to-base ratio is 1.8x (V1404I: 2.0 GHz base / 3.6 GHz boost). The DMI lookup and sanity check are wrapped in a helper, acpi_cpufreq_resolve_max_freq(), which falls through to arch_set_max_freq_ratio() if the DMI value is absent or out of range. Tested on AMD Ryzen Embedded V1780B with v7.0-rc4: Before: cpuinfo_max_freq = 3350000 (base only) After: cpuinfo_max_freq = 3600000 (includes boost) Link: https://www.amd.com/en/products/embedded/ryzen/ryzen-v1000-series.html#specifications Signed-off-by: Henry Tseng <henrytseng@qnap.com> Link: https://patch.msgid.link/20260324090948.1667340-1-henrytseng@qnap.com Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>