Change in coreboot[master]: soc/intel/common/block/pcie/rtd3: Add ModPHY power gate support for RTD3

[Subrata Banik (Code Review)]

Attention is currently required from: Cliff Huang, Maulik V Vaghela, Tim Wawrzynczak, Patrick Rudolph.
Subrata Banik has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/59855 )

Change subject: soc/intel/common/block/pcie/rtd3: Add ModPHY power gate support for RTD3
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Patch Set 3:

(4 comments)

File src/soc/intel/common/block/pcie/rtd3/rtd3.c:

https://review.coreboot.org/c/coreboot/+/59855/comment/0ed5906c_a85bd27a 
PS2, Line 238: 	static bool mutex_created;
> Done

Why we need to initialize to `false` ? Default value itself is false. Isn't it?

#include <stdio.h>
#include <stdbool.h>
int main() {
   static bool a;
   bool b;
   printf("Default value of static variable : %s\n", a == true ? "true" : "false");
   printf("Default value of non-static variable : %s\n", b == true ? "true" : "false");
   return 0;
}

$gcc -o main *.c -lm
$main
Default value of static variable : false
Default value of non-static variable : false

File src/soc/intel/common/block/pcie/rtd3/rtd3.c:

https://review.coreboot.org/c/coreboot/+/59855/comment/e896e1f0_e0af4d3e 
PS3, Line 83: bool enabl
Just thoughts:

Do you really need line #90 if/else clause ?

can't we have like this?

enum modphy_pg_state {
  PG_DISABLE = 0,
  PG_ENABLE = 1,
};

static void pcie_rtd3_enable_modphy_pg(unsigned int pcie_rp, enum modphy_pg_state state)
{
   /* Enter the critical section */
   ....
   acpigen_write_store_int_to_namestr(state, "EMPG");
   acpigen_write_delay_until_namestr_int(100, "AMPG", state);

/* Exit the critical section */
   ....
}

https://review.coreboot.org/c/coreboot/+/59855/comment/cc697db2_a9f21973 
PS3, Line 112: 	pcie_rtd3_enable_modphy_pg(pcie_rp, false);
pcie_rtd3_enable_modphy_pg(pcie_rp, PG_DISABLE);

https://review.coreboot.org/c/coreboot/+/59855/comment/bc3138ec_221bcec2 
PS3, Line 159: 		pcie_rtd3_enable_modphy_pg(pcie_rp, true);
pcie_rtd3_enable_modphy_pg(pcie_rp, PG_ENABLE);