0001-platform-x86-asus-wmi-Add-safety-checks-to-dgpu-egpu.patch

From 9eccb147466f00a13c593ac078d8639e1eafe3a2 Mon Sep 17 00:00:00 2001
From: "Luke D. Jones" <luke@ljones.dev>
Date: Fri, 14 Oct 2022 10:43:09 +1300
Subject: [PATCH] platform/x86: asus-wmi: Add safety checks to dgpu/egpu/mux
 methods

The WMI methods for dgpu_disable, egpu_enable, and gpu_mux_mode have
no internal safety checks. This means it is possible for a user to
set the gpu mux to discreet mode and then disable the dgpu, resulting
in the user having no screen and very little chance of recovery.

This commit adds checks to dgpu_disable and egpu_enable to ensure that
the dgpu can not be disabled if the MUX is in discreet mode, and a
check to gpu_mux_mode to prevent switching to discreet mode if
dgpu_disable is set.

Signed-off-by: Luke D. Jones <luke@ljones.dev>
---
 drivers/platform/x86/asus-wmi.c | 38 +++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
index 6e8e093f96b3..1afc4d40fa1a 100644
--- a/drivers/platform/x86/asus-wmi.c
+++ b/drivers/platform/x86/asus-wmi.c
@@ -615,6 +615,18 @@ static ssize_t dgpu_disable_store(struct device *dev,
 	if (disable > 1)
 		return -EINVAL;
 
+	/*
+	 * The GPU MUX must be checked first, if it is in discreet mode the
+	 * dgpu_disable cannot be set to on or users can end up with no screen.
+	 */
+	result = asus_wmi_get_devstate_simple(asus, ASUS_WMI_DEVID_GPU_MUX);
+	if (result < 0)
+		return result;
+	if (!result && disable) {
+		pr_warn("ASUS MUX is in discreet mode, can not set dgpu_disable on\n");
+		return -EINVAL;
+	}
+
 	err = asus_wmi_set_devstate(ASUS_WMI_DEVID_DGPU, disable, &result);
 	if (err) {
 		pr_warn("Failed to set dgpu disable: %d\n", err);
@@ -663,6 +675,19 @@ static ssize_t egpu_enable_store(struct device *dev,
 	if (enable > 1)
 		return -EINVAL;
 
+	/*
+	 * The GPU MUX must be checked first, if it is in discreet mode the
+	 * egpu_enable cannot be set to on or users can end up with no screen.
+	 * Note: egpu_enable method in WMI also sets dgpu_disable to on.
+	 */
+	result = asus_wmi_get_devstate_simple(asus, ASUS_WMI_DEVID_GPU_MUX);
+	if (result < 0)
+		return result;
+	if (!result && enable) {
+		pr_warn("ASUS MUX is in discreet mode, can not set egpu_enable on\n");
+		return -EINVAL;
+	}
+
 	err = asus_wmi_set_devstate(ASUS_WMI_DEVID_EGPU, enable, &result);
 	if (err) {
 		pr_warn("Failed to set egpu disable: %d\n", err);
@@ -709,6 +734,19 @@ static ssize_t gpu_mux_mode_store(struct device *dev,
 	if (optimus > 1)
 		return -EINVAL;
 
+	/*
+	 * The dgpu_disable must be checked first, if it is enabled the
+	 * gpu MUX can not be set to 0 or users can end up with no screen.
+	 * Note: egpu_enable also switches dgpu_disable to 1 if enabled.
+	 */
+	result = asus_wmi_get_devstate_simple(asus, ASUS_WMI_DEVID_DGPU);
+	if (result < 0)
+		return result;
+	if (result && !optimus) {
+		pr_warn("ASUS dgpu_disable is set, can not switch MUX to discreet mode\n");
+		return -EINVAL;
+	}
+
 	err = asus_wmi_set_devstate(ASUS_WMI_DEVID_GPU_MUX, optimus, &result);
 	if (err) {
 		dev_err(dev, "Failed to set GPU MUX mode: %d\n", err);
-- 
2.37.3