[M] Change in coreboot[main]: mb/google/dedede/var/boxy: Add wait for HPD function

[Joey Peng (Code Review)]

Attention is currently required from: Derek Huang, Reka Norman.

Joey Peng has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/78146?usp=email )

Change subject: mb/google/dedede/var/boxy: Add wait for HPD function
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Patch Set 2:

(2 comments)

File src/mainboard/google/dedede/variants/boxy/ramstage.c:

https://review.coreboot.org/c/coreboot/+/78146/comment/48df3a4d_039c82ab :
PS1, Line 69: wait_for_hpd(GPIO_USB_C0_HPD, display_timeout_ms);
> If only C1 or HDMI is connected, I think this will always time out and add 3s to boot time. […]

Hi Reka, I have tested using HDMI, C0 and C1 ports and the boot time is around 1s.

For cbmem timestamps please reference the bug in commit msg.

https://review.coreboot.org/c/coreboot/+/78146/comment/45edd209_41556076 :
PS1, Line 63: 	static const long display_timeout_ms = 3000;
            : 
            : 	if (display_init_required()
            : 		&& !gpio_get(GPIO_USB_C0_HPD)) {
            : 		/* This has to be done before FSP-S runs. */
            : 		if (google_chromeec_wait_for_displayport(display_timeout_ms)){
            : 			wait_for_hpd(GPIO_USB_C0_HPD, display_timeout_ms);
            : 		}
            : 	}
            : 	else if (display_init_required()
            : 		&& !gpio_get(GPIO_USB_C1_HPD)) {
            : 		/* This has to be done before FSP-S runs. */
            : 		if (google_chromeec_wait_for_displayport(display_timeout_ms)){
            : 			wait_for_hpd(GPIO_USB_C1_HPD, display_timeout_ms);
            : 		}
            : 	}
> It's better to implement this in a separate function, e.g. variant_display_init. […]

Done