From 72251fac062c0b4fe98670ec9e3db3f0702c50ae Mon Sep 17 00:00:00 2001
From: Mark Menzynski <mmenzyns@redhat.com>
Date: Thu, 18 Jul 2019 10:07:39 +0200
Subject: drm/nouveau/gpio: fail if gpu external power is missing
Git-commit: 72251fac062c0b4fe98670ec9e3db3f0702c50ae
Patch-mainline: v5.4-rc1
References: bsc#1152489

Currently, nouveau doesn't check if GPU is missing power. This
patch makes nouveau fail when this happens on latest GPUs.

It checks GPIO function 121 (External Power Emergency), which
should detect power problems on GPU initialization.

This can be disabled with nouveau.config=NvPowerChecks=1

Tested on TU104, GP106 and GF100.

v3:
*  Add config override for disabling power checks

Signed-off-by: Mark Menzynski <mmenzyns@redhat.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 .../nouveau/include/nvkm/subdev/bios/gpio.h   |  1 +
 .../gpu/drm/nouveau/nvkm/subdev/gpio/base.c   | 30 +++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/drivers/gpu/drm/nouveau/include/nvkm/subdev/bios/gpio.h b/drivers/gpu/drm/nouveau/include/nvkm/subdev/bios/gpio.h
index 3f74b2726cf2..d036cdc45201 100644
--- a/drivers/gpu/drm/nouveau/include/nvkm/subdev/bios/gpio.h
+++ b/drivers/gpu/drm/nouveau/include/nvkm/subdev/bios/gpio.h
@@ -7,6 +7,7 @@ enum dcb_gpio_func_name {
 	DCB_GPIO_TVDAC0 = 0x0c,
 	DCB_GPIO_TVDAC1 = 0x2d,
 	DCB_GPIO_FAN_SENSE = 0x3d,
+	DCB_GPIO_EXT_POWER_LOW = 0x79,
 	DCB_GPIO_LOGO_LED_PWM = 0x84,
 	DCB_GPIO_UNUSED = 0xff,
 	DCB_GPIO_VID0 = 0x04,
diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/gpio/base.c b/drivers/gpu/drm/nouveau/nvkm/subdev/gpio/base.c
index 1399d923d446..1337a110c0e3 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/gpio/base.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/gpio/base.c
@@ -23,6 +23,7 @@
  */
 #include "priv.h"
 
+#include <core/option.h>
 #include <core/notify.h>
 
 static int
@@ -182,12 +183,41 @@ static const struct dmi_system_id gpio_reset_ids[] = {
 	{ }
 };
 
+static enum dcb_gpio_func_name power_checks[] = {
+	DCB_GPIO_EXT_POWER_LOW,
+};
+
 static int
 nvkm_gpio_init(struct nvkm_subdev *subdev)
 {
 	struct nvkm_gpio *gpio = nvkm_gpio(subdev);
+	struct dcb_gpio_func func;
+	int ret;
+	int i;
+
 	if (dmi_check_system(gpio_reset_ids))
 		nvkm_gpio_reset(gpio, DCB_GPIO_UNUSED);
+
+	if (nvkm_boolopt(subdev->device->cfgopt, "NvPowerChecks", true)) {
+		for (i = 0; i < ARRAY_SIZE(power_checks); ++i) {
+			ret = nvkm_gpio_find(gpio, 0, power_checks[i],
+					     DCB_GPIO_UNUSED, &func);
+			if (ret)
+				continue;
+
+			ret = nvkm_gpio_get(gpio, 0, func.func, func.line);
+			if (!ret)
+				continue;
+
+			nvkm_error(&gpio->subdev,
+				   "GPU is missing power, check its power "
+				   "cables.  Boot with "
+				   "nouveau.config=NvPowerChecks=0 to "
+				   "disable.\n");
+			return -EINVAL;
+		}
+	}
+
 	return 0;
 }
 
-- 
2.28.0