[M] Change in coreboot[main]: mb/google/fatcat: Add ISH support with FW_CONFIG toggle

[Subrata Banik (Code Review)]

Attention is currently required from: Bora Guvendik, Kapil Porwal, Li1 Feng, Pranava Y N, YH Lin.

Subrata Banik has posted comments on this change by Subrata Banik. ( https://review.coreboot.org/c/coreboot/+/84998?usp=email )

Change subject: mb/google/fatcat: Add ISH support with FW_CONFIG toggle
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Patch Set 3:

(1 comment)

File src/mainboard/google/fatcat/variants/fatcat/fw_config.c:

https://review.coreboot.org/c/coreboot/+/84998/comment/9d7bffb7_17a75e93?usp... :
PS3, Line 457: 	/* GPP_D05:     NC */
             : 	PAD_NC(GPP_D05, NONE),
             : 	/* GPP_D06:     NC */
             : 	PAD_NC(GPP_D06, NONE),
             : 	/* GPP_E05:     NC */
             : 	PAD_NC(GPP_E05, NONE),
> > Can we keep these as default case in gpio.c itself and enable ISH GPIOs when ISH is enabled?
>
> Yes, we can do that, but it won't save anything. Instead, we have a good differentiation here that tells us which GPIOs we should care about when disaligning the ISH.
>
> Anyway, we are not adding these GPIOs in side GPIO.c that means no redundant programming.

But based on your suggestion, it will cause redundant GPIO programming for same PAD if we add it in default inside GPIO.c and then override in fw_config.c isn't it. The current approach is avoiding that need.