[M] Change in coreboot[main]: mb/google/dedede/var/boxy: Wait up for 3s for HPD ready signal

[Derek Huang (Code Review)]

Attention is currently required from: Joey Peng, Paul Menzel, Reka Norman.

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

Change subject: mb/google/dedede/var/boxy: Wait up for 3s for HPD ready signal
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Patch Set 8:

(4 comments)

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

https://review.coreboot.org/c/coreboot/+/78146/comment/97f28a98_872135fe :
PS8, Line 68: 
Are you sure we can get the correct gpio state by get_gpio() without configuring the gpio to input?

https://review.coreboot.org/c/coreboot/+/78146/comment/48051e03_a5a22ec8 :
PS8, Line 70: && !gpio_get(GPIO_USB_C0_HPD)
this is redundant.

https://review.coreboot.org/c/coreboot/+/78146/comment/9abc33f9_14899ed3 :
PS8, Line 74: && !gpio_get(GPIO_USB_C1_HPD
this is redundant

https://review.coreboot.org/c/coreboot/+/78146/comment/9562d637_3d461fbe :
PS8, Line 69: 	if (display_init_required()
            : 		&& !gpio_get(GPIO_USB_C0_HPD)) {
            : 		/* This has to be done before FSP-S runs. */
            : 		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. */
            : 		wait_for_hpd(GPIO_USB_C1_HPD, display_timeout_ms);
            : 	}
If only HDMI is connected, these will always timeout and add 6s delay. It's better to check HDMI HPD as well and call wait_for_hpd only when HDMI is not connected.

Probably we can do, wait_for_hpd() should return 1 when HPD is detected:
```
        if (display_init_required() && !gpio_get(GPIO_HDMI_HPD)) {
                /* This has to be done before FSP-S runs. */
                if(wait_for_hpd(GPIO_USB_C0_HPD, display_timeout_ms))
                        return;
                wait_for_hpd(GPIO_USB_C1_HPD, display_timeout_ms);
        }
```