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 5480 AIO has an ACPI device for one if its UARTs with
the above _HID + _CID. Loading the dell-uart-backlight driver fails with
the following errors:
[ 18.261353] dell_uart_backlight serial0-0: Timed out waiting for response.
[ 18.261356] dell_uart_backlight serial0-0: error -ETIMEDOUT: getting firmware version
[ 18.261359] dell_uart_backlight serial0-0: probe with driver dell_uart_backlight failed with error -110
Indicating that there is no backlight controller board attached to
the UART, while 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: cd8e468efb4f ("ACPI: video: Add Dell UART backlight controller detection")
Cc: All applicable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
drivers/acpi/video_detect.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/drivers/acpi/video_detect.c b/drivers/acpi/video_detect.c
index b70e84e8049a..015bd8e66c1c 100644
--- a/drivers/acpi/video_detect.c
+++ b/drivers/acpi/video_detect.c
@@ -844,6 +844,15 @@ static const struct dmi_system_id video_detect_dmi_table[] = {
* controller board in their ACPI tables (and may even have one), but
* which need native backlight control nevertheless.
*/
+ {
+ /* https://github.com/zabbly/linux/issues/26 */
+ .callback = video_detect_force_native,
+ /* Dell OptiPlex 5480 AIO */
+ .matches = {
+ DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
+ DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 5480 AIO"),
+ },
+ },
{
/* https://bugzilla.redhat.com/show_bug.cgi?id=2303936 */
.callback = video_detect_force_native,
--
2.46.0
