[S] Change in coreboot[main]: mb/google/dedede: Wait for HPD on dexi variant

[Kenneth Chan (Code Review)]

Kenneth Chan has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/78450?usp=email )

Change subject: mb/google/dedede: Wait for HPD on dexi variant
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mb/google/dedede: Wait for HPD on dexi variant

Some Type-C monitors do not immediately assert HPD. If we enter FSP-S
before HDP is asserted, display initialisation may fail. So wait for
HPD.

This is similar to commit b40c6009141e ("mainboard/hatch: Fix puff DP
output on cold boots") on puff, except we don't use
google_chromeec_wait_for_displayport() since that EC command was removed
for TCPMv2 (https://crrev.com/c/4221975). Instead we use the HPD signals
only. By waiting for any HPD signal (Type-C or HDMI), we skip waiting if
HDMI is connected, which is the same behaviour as puff and fizz.

BUG=b:303533815
BRANCH=dedede
TEST=On dexi, connect a display via a Type-C to HDMI dongle and check
the dev and recovery screens are now displayed correctly. Also check the
logs in the following cases:

Cold reboot in dev mode, Type-C to HDMI dongle:
HPD ready after 800 ms

Warm reboot in dev mode, Type-C to HDMI dongle:
HPD ready after 0 ms

Cold/warm reboot in dev mode, direct Type-C:
HPD ready after 0 ms

Cold/warm reboot in dev mode, direct HDMI:
HPD ready after 0 ms

Cold/warm reboot in dev mode, no display:
HPD not ready after 3000 ms. Abort.

Change-Id: Ib4fc071cac98a542072ffbeb6943bff4c988554c
Signed-off-by: Kenneth Chan 
---
M src/mainboard/google/dedede/variants/dexi/gpio.c
1 file changed, 15 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/50/78450/1

diff --git a/src/mainboard/google/dedede/variants/dexi/gpio.c b/src/mainboard/google/dedede/variants/dexi/gpio.c
index 89a7a77..2998592 100644
--- a/src/mainboard/google/dedede/variants/dexi/gpio.c
+++ b/src/mainboard/google/dedede/variants/dexi/gpio.c
@@ -91,3 +91,18 @@
    *num = ARRAY_SIZE(gpio_table);
    return gpio_table;
 }
+
+static const gpio_t hpd_gpios[] = {
+	/* HDMI1 */
+	GPP_A17,
+	/* HDMI2 */
+	GPP_A16,
+	/* USB C0 */
+	GPP_B23,
+};
+
+const gpio_t *variant_hpd_gpios(size_t *num)
+{
+	*num = ARRAY_SIZE(hpd_gpios);
+	return hpd_gpios;
+}