From 1247616304ebf9a8839a6808be2f12912b1d98f8 Mon Sep 17 00:00:00 2001 From: Furquan Shaikh Date: Tue, 23 Jun 2020 11:07:22 -0700 Subject: [PATCH] mb/google/zork: Reconfigure PCIE_RST1_L as GPO driven low on sleep path This change configures PCIE_RST1_L as GPO driven low on the sleep path. This is required to keep PERST# asserted to devices until coreboot deasserts it on S3 resume path. Without this change, on S3 resume, PCIE_RST1_L gets deasserted sooner than required resulting in violation of PCIe reset timings. With this change, the behavior of PCIE_RST1_L is as follows: 1. GPIO27 is configured as NF (PCIE_RST1_L) in coreboot bootblock/romstage and driven high. 2. On S3 entry, GPIO27 is configured as GPO driven low. * Boot out of G3: Timing should be met since GPIO_27 is pulled down by default until coreboot configures it. * S3 resume: Timing should be met since GPIO_27 is configured as GPO low and it retains state across S3 entry/exit. So, should be low until coreboot configures it. * Warm reset: Timing should be met since it is configured as NF. So, hardware guarantees the reset timing as seen in "warm reset.jpg" in #46. BUG=b:152582706 Signed-off-by: Furquan Shaikh Change-Id: Ia0ad1522edc438fd054d927ef4a2ab5c27329c00 Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/coreboot/+/2261116 Reviewed-by: Aaron Durbin Commit-Queue: Furquan Shaikh Tested-by: Furquan Shaikh Reviewed-on: https://review.coreboot.org/c/coreboot/+/42934 Tested-by: build bot (Jenkins) Reviewed-by: Aaron Durbin --- .../google/zork/variants/baseboard/gpio_baseboard_common.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/src/mainboard/google/zork/variants/baseboard/gpio_baseboard_common.c b/src/mainboard/google/zork/variants/baseboard/gpio_baseboard_common.c index e43b0b4cff..1dd2dd5b89 100644 --- a/src/mainboard/google/zork/variants/baseboard/gpio_baseboard_common.c +++ b/src/mainboard/google/zork/variants/baseboard/gpio_baseboard_common.c @@ -34,6 +34,8 @@ const __weak struct soc_amd_gpio *variant_early_gpio_table(size_t *size) static const struct soc_amd_gpio gpio_sleep_table[] = { /* PEN_POWER_EN */ PAD_GPO(GPIO_5, LOW), + /* PCIE_RST1_L */ + PAD_GPO(GPIO_27, LOW), /* EN_PWR_CAMERA */ PAD_GPO(GPIO_76, LOW), };