Change in coreboot[master]: soc/intel/common/block/acpi: Add LPM requirements support to PEPD _DSM

[Angel Pons (Code Review)]

Attention is currently required from: Furquan Shaikh, Tim Wawrzynczak, Michael Niewöhner, Patrick Rudolph, Karthik Ramasubramanian.
Angel Pons has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/56005 )

Change subject: soc/intel/common/block/acpi: Add LPM requirements support to PEPD _DSM
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Patch Set 3:

(3 comments)

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

https://review.coreboot.org/c/coreboot/+/56005/comment/dce81902_d8358a49 
PS3, Line 32: 	uint32_t *reg = calloc(LPM_REGISTERS_COUNT, sizeof(uint32_t));
Hmmm, I don't like using dynamically allocating memory when the buffer size is known at compile-time. Given that this is a static function, I would have the array as a local variable in `generate_acpi_power_engine()` and pass it to this function as a parameter.

Another option would be to declare the array in this function as static, and return a pointer to it. This would work because static variables in a function persist after the function returns, but I'm not sure how clean it would be.

https://review.coreboot.org/c/coreboot/+/56005/comment/090287ac_41ca74f5 
PS3, Line 183: LPM_REGISTERS_COUNT * sizeof(uint32_t)
I'd really like to avoid open-coding the size of this thing.

https://review.coreboot.org/c/coreboot/+/56005/comment/1914a669_4a295979 
PS3, Line 197: DSM_UUID(PEP_S0IX_UUID, pep_s0ix, ARRAY_SIZE(pep_s0ix), (void *)reg),
> nit: Is there value in exposing this _DSM with 0 supported functions if !SOC_INTEL_COMMON_BLOCK_ACPI […]

+1