On Mon, Feb 21, 2022 at 10:17:37PM +0100, Mark Kettenis wrote:
The stdout-path property in the device tree does not necessarily point at a serial device. On machines such as the Apple M1 laptops where the serial port isn't easy to access and users expect to see console output on the integrated display stdout-path may point at the device tree node for the framebuffer for example.
If stdout-path does not point at a node for a serial device, the serial_check_stdout() will not find a bound device and will drop down into code that attempts to use lists_bind_fdt() to bind a device anyway. However, that fallback code does not check that the uclass of the device is UCLASS_SERIAL. So if stdout-path points at the framebuffer instead of the serial device it will return a UCLASS_VIDEO device. Since the code that calls this function expects the returned device to be a UCLASS_SERIAL device, U-Boot will crash as soon as it attempts to send output to the console.
Add a check here to verify that the uclass of the bound device really is UCLASS_SERIAL. If it isn't, serial_check_stdout() will return an error and serial_find_console_or_panic() will use the serial device with sequence number 0 as the console and all is fine.
Signed-off-by: Mark Kettenis kettenis@openbsd.org Reviewed-by: Simon Glass sjg@chromium.org
Applied to u-boot/master, thanks!