Merge tag 'acpi-6.3-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull ACPI fixes from Rafael Wysocki:
 "Fix the ACPI backlight override mechanism for the cases when
  acpi_backlight=video is set through the kernel command line or a DMI
  quirk and add backlight quirks for Apple iMac14,1 and iMac14,2 and
  Lenovo ThinkPad W530 (Hans de Goede)"

* tag 'acpi-6.3-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPI: video: Add acpi_backlight=video quirk for Lenovo ThinkPad W530
  ACPI: video: Add acpi_backlight=video quirk for Apple iMac14,1 and iMac14,2
  ACPI: video: Make acpi_backlight=video work independent from GPU driver
  ACPI: video: Add auto_detect arg to __acpi_video_get_backlight_type()

drivers/acpi/acpi_video.c

@@ -1984,6 +1984,7 @@ static int instance;
 static int acpi_video_bus_add(struct acpi_device *device)
 {
 	struct acpi_video_bus *video;
+	bool auto_detect;
 	int error;
 	acpi_status status;
 
@@ -2045,10 +2046,20 @@ static int acpi_video_bus_add(struct acpi_device *device)
 	mutex_unlock(&video_list_lock);
 
 	/*
-	 * The userspace visible backlight_device gets registered separately
-	 * from acpi_video_register_backlight().
+	 * If backlight-type auto-detection is used then a native backlight may
+	 * show up later and this may change the result from video to native.
+	 * Therefor normally the userspace visible /sys/class/backlight device
+	 * gets registered separately by the GPU driver calling
+	 * acpi_video_register_backlight() when an internal panel is detected.
+	 * Register the backlight now when not using auto-detection, so that
+	 * when the kernel cmdline or DMI-quirks are used the backlight will
+	 * get registered even if acpi_video_register_backlight() is not called.
 	 */
 	acpi_video_run_bcl_for_osi(video);
+	if (__acpi_video_get_backlight_type(false, &auto_detect) == acpi_backlight_video &&
+	    !auto_detect)
+		acpi_video_bus_register_backlight(video);
+
 	acpi_video_bus_add_notify_handler(video);
 
 	return 0;

drivers/acpi/video_detect.c

@@ -276,6 +276,43 @@ static const struct dmi_system_id video_detect_dmi_table[] = {
 		},
 	},
 
+	/*
+	 * Models which need acpi_video backlight control where the GPU drivers
+	 * do not call acpi_video_register_backlight() because no internal panel
+	 * is detected. Typically these are all-in-ones (monitors with builtin
+	 * PC) where the panel connection shows up as regular DP instead of eDP.
+	 */
+	{
+	 .callback = video_detect_force_video,
+	 /* Apple iMac14,1 */
+	 .matches = {
+		DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
+		DMI_MATCH(DMI_PRODUCT_NAME, "iMac14,1"),
+		},
+	},
+	{
+	 .callback = video_detect_force_video,
+	 /* Apple iMac14,2 */
+	 .matches = {
+		DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
+		DMI_MATCH(DMI_PRODUCT_NAME, "iMac14,2"),
+		},
+	},
+
+	/*
+	 * Older models with nvidia GPU which need acpi_video backlight
+	 * control and where the old nvidia binary driver series does not
+	 * call acpi_video_register_backlight().
+	 */
+	{
+	 .callback = video_detect_force_video,
+	 /* ThinkPad W530 */
+	 .matches = {
+		DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
+		DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad W530"),
+		},
+	},
+
 	/*
 	 * These models have a working acpi_video backlight control, and using
 	 * native backlight causes a regression where backlight does not work
@@ -782,7 +819,7 @@ static bool prefer_native_over_acpi_video(void)
  * Determine which type of backlight interface to use on this system,
  * First check cmdline, then dmi quirks, then do autodetect.
  */
-static enum acpi_backlight_type __acpi_video_get_backlight_type(bool native)
+enum acpi_backlight_type __acpi_video_get_backlight_type(bool native, bool *auto_detect)
 {
 	static DEFINE_MUTEX(init_mutex);
 	static bool nvidia_wmi_ec_present;
@@ -807,6 +844,9 @@ static enum acpi_backlight_type __acpi_video_get_backlight_type(bool native)
 		native_available = true;
 	mutex_unlock(&init_mutex);
 
+	if (auto_detect)
+		*auto_detect = false;
+
 	/*
 	 * The below heuristics / detection steps are in order of descending
 	 * presedence. The commandline takes presedence over anything else.
@@ -818,6 +858,9 @@ static enum acpi_backlight_type __acpi_video_get_backlight_type(bool native)
 	if (acpi_backlight_dmi != acpi_backlight_undef)
 		return acpi_backlight_dmi;
 
+	if (auto_detect)
+		*auto_detect = true;
+
 	/* Special cases such as nvidia_wmi_ec and apple gmux. */
 	if (nvidia_wmi_ec_present)
 		return acpi_backlight_nvidia_wmi_ec;
@@ -837,15 +880,4 @@ static enum acpi_backlight_type __acpi_video_get_backlight_type(bool native)
 	/* No ACPI video/native (old hw), use vendor specific fw methods. */
 	return acpi_backlight_vendor;
 }
-
-enum acpi_backlight_type acpi_video_get_backlight_type(void)
-{
-	return __acpi_video_get_backlight_type(false);
-}
-EXPORT_SYMBOL(acpi_video_get_backlight_type);
-
-bool acpi_video_backlight_use_native(void)
-{
-	return __acpi_video_get_backlight_type(true) == acpi_backlight_native;
-}
-EXPORT_SYMBOL(acpi_video_backlight_use_native);
+EXPORT_SYMBOL(__acpi_video_get_backlight_type);

include/acpi/video.h

@@ -59,8 +59,6 @@ extern void acpi_video_unregister(void);
 extern void acpi_video_register_backlight(void);
 extern int acpi_video_get_edid(struct acpi_device *device, int type,
 			       int device_id, void **edid);
-extern enum acpi_backlight_type acpi_video_get_backlight_type(void);
-extern bool acpi_video_backlight_use_native(void);
 /*
  * Note: The value returned by acpi_video_handles_brightness_key_presses()
  * may change over time and should not be cached.
@@ -69,6 +67,19 @@ extern bool acpi_video_handles_brightness_key_presses(void);
 extern int acpi_video_get_levels(struct acpi_device *device,
 				 struct acpi_video_device_brightness **dev_br,
 				 int *pmax_level);
+
+extern enum acpi_backlight_type __acpi_video_get_backlight_type(bool native,
+								bool *auto_detect);
+
+static inline enum acpi_backlight_type acpi_video_get_backlight_type(void)
+{
+	return __acpi_video_get_backlight_type(false, NULL);
+}
+
+static inline bool acpi_video_backlight_use_native(void)
+{
+	return __acpi_video_get_backlight_type(true, NULL) == acpi_backlight_native;
+}
 #else
 static inline void acpi_video_report_nolcd(void) { return; };
 static inline int acpi_video_register(void) { return -ENODEV; }