Hi, There has been a somewhat longstanding issue on the Pyra, where any kind of soft reboot causes it to hang (only a true power off and on again works). The background is at https://projects.goldelico.com/p/gta04-kernel/issues/876/. The failure is typically of the following form: https://dev.pyra-handheld.com/snippets/765 (the exact failure sequence has changed a bit in different kernel versions). With the pertinent line being: [ 0.000000] clock: dpll_abe_ck failed transition to 'locked' This only happens on the Pyra, not the OMAP5 uEVM. This seems to be because the Pyra uses TIMER8 for the backlight PWM. Looking around at some other OMAP5 clocking code, I found https://gitlab.com/linux-omap4-dev/omapboot/-/blob/kexec_support/arch/omap5/clock.c#L335 This to me suggests that both CM_CLKSEL_ABE_PLL_REF and CM_CLKSEL_WKUPAON should be set to 1. I found that only CM_CLKSEL_ABE_PLL_REF was 1 and CM_CLKSEL_WKUPAON was 0 at the point of checking DPLL lock. I wrote a very hacky patch just to force CM_CLKSEL_WKUPAON to 1 at startup, to test this theory: https://dev.pyra-handheld.com/snippets/770 (breaking every rule in the book, I know :) And indeed with this reboots now seem to work fine. The question is, what is the correct way/place to deal with this? Is this even a Linux issue at all, or should U-Boot be doing something here? A quick glance suggests that nothing in the kernel deals with CM_CLKSEL_WKUPAON at all but I may have missed something. Best David
