Dell All In One (AIO) models released after 2017 may 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")
The Dell OptiPlex 7760 AIO has an ACPI device for one if its UARTs with
the above _HID + _CID. Loading the dell-uart-backlight driver shows that
there actually is a backlight controller board attached to the UART,
which reports a firmware version of "G&MX01-V15".
But the backlight controller board does not actually control the backlight
brightness and the GPU's native backlight control method does work.
Add a quirk to use the GPU's native backlight control method on this model.
Fixes: 484bae9e4d6a ("platform/x86: Add new Dell UART backlight driver")
Closes: https://bugzilla.redhat.com/show_bug.cgi?id=2303936
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
drivers/acpi/video_detect.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/drivers/acpi/video_detect.c b/drivers/acpi/video_detect.c
index e509dcbf3090..674b9db7a1ef 100644
--- a/drivers/acpi/video_detect.c
+++ b/drivers/acpi/video_detect.c
@@ -823,6 +823,21 @@ static const struct dmi_system_id video_detect_dmi_table[] = {
},
},
+ /*
+ * Dell AIO (All in Ones) which advertise an UART attached backlight
+ * controller board in their ACPI tables (and may even have one), but
+ * which need native backlight control nevertheless.
+ */
+ {
+ /* https://bugzilla.redhat.com/show_bug.cgi?id=2303936 */
+ .callback = video_detect_force_native,
+ /* Dell OptiPlex 7760 AIO */
+ .matches = {
+ DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
+ DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 7760 AIO"),
+ },
+ },
+
/*
* Models which have nvidia-ec-wmi support, but should not use it.
* Note this indicates a likely firmware bug on these models and should
--
2.46.0
