On 03/15/2016 08:36 PM, Stephen Warren wrote:
On 03/13/2016 07:16 PM, Eric Anholt wrote:
For Raspberry Pi, we had the input clock rate to the pl011 fixed in the rpi.c file, but it may be changed by firmware due to user changes to config.txt. Since the firmware always sets up the uart (default 115200 output unless the user changes it), we can just skip our own uart init to simplify the boot process and more reliably get serial output.
Tested-by: Stephen Warren swarren@wwwdotorg.org # on RPi B+ and RPi 2
Sorry, I take this Tested-by back. With the latest firmware (which has some modifications intended to initialize either the PL01x or the mini UART depending on which the kernel will actually use), this patch causes U-Boot not to boot at all. I'm pretty sure this is a FW bug (since even without this patch the UART doesn't work, but U-Boot does at least boot and can be used over HDMI/usbkbd), but I'd still prefer not to apply this until the FW is working again and we can double-check everything.
Hopefully this will be resolved in https://github.com/raspberrypi/firmware/issues/553 soon.