Add upstreamed gmux patch

Workaround until the Apple-gmux patches are put here
2026-04-30 13:52:11 -07:00 · 2022-12-15 18:08:09 +05:30
parent 1918b48554
commit 5c2a3930cb
1 changed files with 82 additions and 0 deletions
@@ -0,0 +1,82 @@
+From 6833726fd944d98c4722e166119ab87aced01deb Mon Sep 17 00:00:00 2001
+From: Hans de Goede <hdegoede@redhat.com>
+Date: Wed, 14 Dec 2022 22:45:47 +0100
+Subject: [PATCH] ACPI: video: Fix Apple GMUX backlight detection
+
+The apple-gmux driver only binds to old GMUX devices which have an
+IORESOURCE_IO resource (using inb()/outb()) rather then memory-mapped
+IO (IORESOURCE_MEM).
+
+T2 MacBooks use the new style GMUX devices (with IORESOURCE_MEM access),
+so these are not supported by the apple-gmux driver. This is not a problem
+since they have working ACPI video backlight support.
+
+But the apple_gmux_present() helper only checks if an ACPI device with
+the "APP000B" HID is present, causing acpi_video_get_backlight_type()
+to return acpi_backlight_apple_gmux disabling the acpi_video backlight
+device.
+
+Add a new apple_gmux_backlight_present() helper which checks that
+the "APP000B" device actually is an old GMUX device with an IORESOURCE_IO
+resource.
+
+This fixes the acpi_video0 backlight no longer registering on T2 MacBooks.
+
+Fixes: 21245df307cb ("ACPI: video: Add Apple GMUX brightness control detection")
+Reported-by: Aditya Garg <gargaditya08@live.com>
+Signed-off-by: Hans de Goede <hdegoede@redhat.com>
+---
+ drivers/acpi/video_detect.c | 23 ++++++++++++++++++++++-
+ 1 file changed, 22 insertions(+), 1 deletion(-)
+
+diff --git a/drivers/acpi/video_detect.c b/drivers/acpi/video_detect.c
+index a934bbc9dd37..1b78c7434492 100644
+--- a/drivers/acpi/video_detect.c
+++ b/drivers/acpi/video_detect.c
+@@ -34,6 +34,7 @@
+ #include <linux/module.h>
+ #include <linux/pci.h>
+ #include <linux/platform_data/x86/nvidia-wmi-ec-backlight.h>
+#include <linux/pnp.h>
+ #include <linux/types.h>
+ #include <linux/workqueue.h>
+ #include <acpi/video.h>
+@@ -105,6 +106,26 @@ static bool nvidia_wmi_ec_supported(void)
+ }
+ #endif
+ 
+static bool apple_gmux_backlight_present(void)
+{
+	struct acpi_device *adev;
+	struct device *dev;
+
+	adev = acpi_dev_get_first_match_dev(GMUX_ACPI_HID, NULL, -1);
+	if (!adev)
+		return false;
+
+	dev = acpi_get_first_physical_node(adev);
+	if (!dev)
+		return false;
+
+	/*
+	 * drivers/platform/x86/apple-gmux.c only supports old style
+	 * Apple GMUX with an IO-resource.
+	 */
+	return pnp_get_resource(to_pnp_dev(dev), IORESOURCE_IO, 0) != NULL;
+}
+
+ /* Force to use vendor driver when the ACPI device is known to be
+  * buggy */
+ static int video_detect_force_vendor(const struct dmi_system_id *d)
+@@ -767,7 +788,7 @@ static enum acpi_backlight_type __acpi_video_get_backlight_type(bool native)
+ 	if (nvidia_wmi_ec_present)
+ 		return acpi_backlight_nvidia_wmi_ec;
+ 
+-	if (apple_gmux_present())
+	if (apple_gmux_backlight_present())
+ 		return acpi_backlight_apple_gmux;
+ 
+ 	/* Use ACPI video if available, except when native should be preferred. */
+-- 
+2.38.1
+