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[1/3] ACPI: video: Add Dell UART backlight controller detection

Message ID 20240814190159.15650-2-hdegoede@redhat.com (mailing list archive)
State In Next, archived
Delegated to: Rafael Wysocki
Headers show
Series ACPI/video / platform/x86: Add backlight=native quirk for Dell OptiPlex 7760 AIO | expand

Commit Message

Hans de Goede Aug. 14, 2024, 7:01 p.m. UTC
Dell All In One (AIO) models released after 2017 use a backlight
controller board connected to an UART.

In DSDT this uart port will be defined as:

   Name (_HID, "DELL0501")
   Name (_CID, EisaId ("PNP0501")

Commit 484bae9e4d6a ("platform/x86: Add new Dell UART backlight driver")
has added support for this, but I neglected to tie this into
acpi_video_get_backlight_type().

Now the first AIO has turned up which has not only the DSDT bits for this,
but also an actual controller attached to the UART, yet it is not using
this controller for backlight control.

Add support to acpi_video_get_backlight_type() for a new dell_uart
backlight type. So that the existing infra to override the backlight
control method on the commandline or with DMI quirks can be used.

Fixes: 484bae9e4d6a ("platform/x86: Add new Dell UART backlight driver")
Cc: stable@vger.kernel.org
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/acpi/video_detect.c | 7 +++++++
 include/acpi/video.h        | 1 +
 2 files changed, 8 insertions(+)
diff mbox series

Patch

diff --git a/drivers/acpi/video_detect.c b/drivers/acpi/video_detect.c
index c11cbe5b6eaa..e509dcbf3090 100644
--- a/drivers/acpi/video_detect.c
+++ b/drivers/acpi/video_detect.c
@@ -54,6 +54,8 @@  static void acpi_video_parse_cmdline(void)
 		acpi_backlight_cmdline = acpi_backlight_nvidia_wmi_ec;
 	if (!strcmp("apple_gmux", acpi_video_backlight_string))
 		acpi_backlight_cmdline = acpi_backlight_apple_gmux;
+	if (!strcmp("dell_uart", acpi_video_backlight_string))
+		acpi_backlight_cmdline = acpi_backlight_dell_uart;
 	if (!strcmp("none", acpi_video_backlight_string))
 		acpi_backlight_cmdline = acpi_backlight_none;
 }
@@ -918,6 +920,7 @@  enum acpi_backlight_type __acpi_video_get_backlight_type(bool native, bool *auto
 	static DEFINE_MUTEX(init_mutex);
 	static bool nvidia_wmi_ec_present;
 	static bool apple_gmux_present;
+	static bool dell_uart_present;
 	static bool native_available;
 	static bool init_done;
 	static long video_caps;
@@ -932,6 +935,7 @@  enum acpi_backlight_type __acpi_video_get_backlight_type(bool native, bool *auto
 				    &video_caps, NULL);
 		nvidia_wmi_ec_present = nvidia_wmi_ec_supported();
 		apple_gmux_present = apple_gmux_detect(NULL, NULL);
+		dell_uart_present = acpi_dev_present("DELL0501", NULL, -1);
 		init_done = true;
 	}
 	if (native)
@@ -962,6 +966,9 @@  enum acpi_backlight_type __acpi_video_get_backlight_type(bool native, bool *auto
 	if (apple_gmux_present)
 		return acpi_backlight_apple_gmux;
 
+	if (dell_uart_present)
+		return acpi_backlight_dell_uart;
+
 	/* Use ACPI video if available, except when native should be preferred. */
 	if ((video_caps & ACPI_VIDEO_BACKLIGHT) &&
 	     !(native_available && prefer_native_over_acpi_video()))
diff --git a/include/acpi/video.h b/include/acpi/video.h
index 3d538d4178ab..044c463138df 100644
--- a/include/acpi/video.h
+++ b/include/acpi/video.h
@@ -50,6 +50,7 @@  enum acpi_backlight_type {
 	acpi_backlight_native,
 	acpi_backlight_nvidia_wmi_ec,
 	acpi_backlight_apple_gmux,
+	acpi_backlight_dell_uart,
 };
 
 #if IS_ENABLED(CONFIG_ACPI_VIDEO)