Hi, On 5/13/24 4:46 PM, Hans de Goede wrote: > Hi All, > > I recently learned that some Dell AIOs (1) use a backlight controller board > connected to an UART. Canonical even submitted a driver for this in 2017: > https://lkml.org/lkml/2017/10/26/78 > > This UART has a DELL0501 HID with CID set to PNP0501 so that the UART is > still handled by 8250_pnp.c. Unfortunately there is no separate ACPI device > with an UartSerialBusV2() resource to model the backlight-controller. An > ACPI quirk has been merged recently to deal with this and create a serdev > controller for the UART despite the missing UartSerialBusV2() resource: > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=99b572e6136eab69a8c91d72cf8595b256e304b5 > > Patch 1 in this series adds a driver binding to the "dell-uart-backlight" > device created by this quirk. This drivers creates a serdev-device for > the DELL0501 serdev-controller and registers a serdev backlight driver > which binds to this serdev-device. > > Patch 2 contains a small emulator for the UART attached backlight > controller found on this Dell AOIs, I wrote and used this to develop > the driver since I did not have access to such an AOI myself. > > This has been successfully tested by Roman Bogoyev (who originally > reported the missing driver to me by email) on a Dell Inspiron 27 7000 > (7790) and by Kai-Heng Feng on a newer Dell AOI model. > > Changes in v3: > - Rework dell_uart_bl_receive() loop (based on suggestions from Ilpo) > - Address some more review remarks from Andy > > Changes in v2: > - Address all the review-remarks Ilpo and Andy had on Patch 1/2, > thank you for the extensive review Ilpo and Andy I've added this series to my review-hans (soon to be for-next) branch now. Regards, Hans > Hans de Goede (2): > platform/x86: Add new Dell UART backlight driver > tools arch x86: Add dell-uart-backlight-emulator > > drivers/platform/x86/dell/Kconfig | 15 + > drivers/platform/x86/dell/Makefile | 1 + > .../platform/x86/dell/dell-uart-backlight.c | 398 ++++++++++++++++++ > .../dell-uart-backlight-emulator/.gitignore | 1 + > .../x86/dell-uart-backlight-emulator/Makefile | 19 + > .../x86/dell-uart-backlight-emulator/README | 46 ++ > .../dell-uart-backlight-emulator.c | 163 +++++++ > 7 files changed, 643 insertions(+) > create mode 100644 drivers/platform/x86/dell/dell-uart-backlight.c > create mode 100644 tools/arch/x86/dell-uart-backlight-emulator/.gitignore > create mode 100644 tools/arch/x86/dell-uart-backlight-emulator/Makefile > create mode 100644 tools/arch/x86/dell-uart-backlight-emulator/README > create mode 100644 tools/arch/x86/dell-uart-backlight-emulator/dell-uart-backlight-emulator.c >
