Change in coreboot[master]: soc/intel/common: Implement ACPI CPPCv3 package to support hybrid core

[Arthur Heymans (Code Review)]

Attention is currently required from: Nico Huber, Tim Wawrzynczak, Paul Menzel, Ravindra, Sridhar Siricilla, Subrata Banik, Arthur Heymans, Michael Niewöhner, Patrick Rudolph.
Arthur Heymans has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/59359 )

Change subject: soc/intel/common: Implement ACPI CPPCv3 package to support hybrid core
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Patch Set 10:

(1 comment)

File src/soc/intel/common/block/acpi/cpu_hybrid.c:

https://review.coreboot.org/c/coreboot/+/59359/comment/65d82019_b249bbf5 
PS3, Line 102: 	acpi_get_cpu_hybrid_info(&cpu_hybrid_info);
             : 	acpigen_write_method(XPPC_PACKAGE_NAME, 1);
             : 
             : 	if (cpu_is_nominal_freq_supported()) {
             : 
             : 		/*
             : 		 * If Nominal Frequency is supported, update Nominal Frequency and set core's
             : 		 * Nominal Performance to a scaling factor which depends on core type(big or
             : 		 * small).
             : 		 */
             : 		acpigen_set_package_element_int(CPPC_PACKAGE_NAME, 22,
             : 				cpu_hybrid_info.nominal_freq);
             : 
             : 		/* LOCAL2_OP = (CORE >> core_id) & 1 */
             : 		acpigen_emit_byte(SHIFT_RIGHT_OP);
             : 		acpigen_write_integer(cpu_hybrid_info.type_mask);
             : 		acpigen_emit_byte(ARG0_OP);
             : 		acpigen_emit_byte(LOCAL1_OP);
             : 		acpigen_write_and(LOCAL1_OP, ONE_OP, LOCAL2_OP);
             : 
             : 		/*
             : 		 * If core id is big Core, then set big core's scaling factor
             : 		 * to core's nominal frequency otherwise set small core's scaling factor.
             : 		 */
             : 		acpigen_write_if_lequal_op_int(LOCAL2_OP, 1);
             : 		acpigen_set_package_element_int(CPPC_PACKAGE_NAME, 3,
             : 				cpu_hybrid_info.big_core_nom_perf);
             : 		acpigen_write_else();
             : 		acpigen_set_package_element_int(CPPC_PACKAGE_NAME, 3,
             : 				cpu_hybrid_info.small_core_nom_perf);
             : 		acpigen_pop_len();
             : 	}
             : 
             : 	acpigen_emit_byte(RETURN_OP);
             : 	acpigen_emit_namestring(CPPC_PACKAGE_NAME);
             : 	acpigen_pop_len();
> Implementing CPPCv3 package generation in the SSDT gives more flexibility. For example, CPPCv3 generation is not required for all the SoC variants (ADL-N/ADL-P) within the same CPU family(ADL). So, the CPPCv3 generation can be controlled through SoC function cpu_is_nominal_freq_supported() based on the SoC variant.

I don't see the code doing that.
Also why would implementing it fully in SSDT be more flexible than a DSDT implemenation consuming SSDT namespace (using the external keyword)?