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Diffstat (limited to 'tools/arch/x86/dell-uart-backlight-emulator/README')
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diff --git a/tools/arch/x86/dell-uart-backlight-emulator/README b/tools/arch/x86/dell-uart-backlight-emulator/README new file mode 100644 index 000000000000..c0d8e52046ee --- /dev/null +++ b/tools/arch/x86/dell-uart-backlight-emulator/README @@ -0,0 +1,46 @@ +Emulator for DELL0501 UART attached backlight controller +-------------------------------------------------------- + +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") + +With the DELL0501 indicating that we are dealing with an UART with +the backlight controller board attached. + +This small emulator allows testing +the drivers/platform/x86/dell/dell-uart-backlight.c driver without access +to an actual Dell All In One. + +This requires: +1. A (desktop) PC with a 16550 UART on the motherboard and a standard DB9 + connector connected to this UART. +2. A DB9 NULL modem cable. +3. A second DB9 serial port, this can e.g. be a USB to serial converter + with a DB9 connector plugged into the same desktop PC. +4. A DSDT overlay for the desktop PC replacing the _HID of the 16550 UART + ACPI Device() with "DELL0501" and adding a _CID of "PNP0501", see + DSDT.patch for an example of the necessary DSDT changes. + +With everything setup and the NULL modem cable connected between +the 2 serial ports run: + +./dell-uart-backlight-emulator <path-to-/dev/tty*S#-for-second-port> + +For example when using an USB to serial converter for the second port: + +./dell-uart-backlight-emulator /dev/ttyUSB0 + +And then (re)load the dell-uart-backlight driver: + +sudo rmmod dell-uart-backlight; sudo modprobe dell-uart-backlight dyndbg + +After this check "dmesg" to see if the driver correctly received +the firmware version string from the emulator. If this works there +should be a /sys/class/backlight/dell_uart_backlight/ directory now +and writes to the brightness or bl_power files should be reflected +by matching output from the emulator. |