Change in coreboot[master]: mb/google/guybrush: Switch eSPI ALERT# to in-band

[Felix Held (Code Review)]

Felix Held has submitted this change. ( https://review.coreboot.org/c/coreboot/+/52955 )

Change subject: mb/google/guybrush: Switch eSPI ALERT# to in-band
......................................................................

mb/google/guybrush: Switch eSPI ALERT# to in-band

Using the push-pull alert was causing leakages when in S0i3. This is
because the EC drives ALERT#, so when the AP enters S0i3, the extra
current leaks into the SoC and ends up turning on the power regulators.
By using in-band ALERT#, the EC no longer drives this pin high, thus
fixing the leak. We could also have used an open drain alert, but the
rise time is less than ideal.

BUG=b:187122344, b:186135022
TEST=Measure S0i3 power on guybrush and validate it's no longer high.

Signed-off-by: Raul E Rangel 
Change-Id: I6de771aeda8feca062652f0ea9eb57d31cb68562
Reviewed-on: https://review.coreboot.org/c/coreboot/+/52955
Tested-by: build bot (Jenkins) 
Reviewed-by: Karthik Ramasubramanian 
Reviewed-by: Felix Held 
Reviewed-by: Furquan Shaikh 
Reviewed-by: Rob Barnes 
---
M src/mainboard/google/guybrush/variants/baseboard/devicetree.cb
1 file changed, 1 insertion(+), 1 deletion(-)

Approvals:
  build bot (Jenkins): Verified
  Felix Held: Looks good to me, approved
  Furquan Shaikh: Looks good to me, approved
  Karthik Ramasubramanian: Looks good to me, approved
  Rob Barnes: Looks good to me, approved

diff --git a/src/mainboard/google/guybrush/variants/baseboard/devicetree.cb b/src/mainboard/google/guybrush/variants/baseboard/devicetree.cb
index 061b275..88a0a1c 100644
--- a/src/mainboard/google/guybrush/variants/baseboard/devicetree.cb
+++ b/src/mainboard/google/guybrush/variants/baseboard/devicetree.cb
@@ -35,7 +35,7 @@
    	.io_mode = ESPI_IO_MODE_QUAD,
    	.op_freq_mhz = ESPI_OP_FREQ_33_MHZ,
    	.crc_check_enable = 1,
-		.alert_pin = ESPI_ALERT_PIN_PUSH_PULL,
+		.alert_pin = ESPI_ALERT_PIN_IN_BAND,
    	.periph_ch_en = 1,
    	.vw_ch_en = 1,
    	.oob_ch_en = 0,