Hi, * David Shah <dave@xxxxxx> [200723 14:08]: > 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. OK good to hear this one is tracked down now. > 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. Not sure if CM_CLKSEL_WKUPAON can be always configured to 1 for ABE usage. So probably configuring it with assigned-clocks does not sound like a right solution. If it only needs to be configured to 1 for reboot, sounds like it should be set in omap44xx_restart(). And we should also set it to 1 for omap4 too. Regards, Tony
