omap4-panda-es boot issues with v3.15-rc4

[Kevin Hilman]

On Thu, May 8, 2014 at 8:31 AM, Kevin Hilman <khilman at linaro.org> wrote:
> Roger Quadros <rogerq at ti.com> writes:
>
>> Hi,
>>
>> Nishant pointed me to a booting issue with omap4-panda-es on linux-next but I'm observing
>> similar issues, although less frequent, with v3.15-rc4 as well.
>>
>> Configuration:
>>
>> - kernel v3.15-rc4 or linux-next (20140507)
>> - multi_v7_defconfig with LEDS_TRIGGER_HEARTBEAT and LEDS_GPIO enabled
>> - u-boot/master       173d294b94cf
>>
>> Observations:
>>
>> - Out of 10 boots a few may not succeed and hang midway without any warnings. Heartbeat LED stops.
>> e.g. http://www.hastebin.com/ebumojegoq.vhdl
>>
>> - Hang more noticeable on linux-next (20140507) than on v3.15-rc4
>
> I've beeen noticing the same thing for awhile with my boot tests.  For
> me, next-20140508 is failing most of the time now.
>
>> - Hang more noticeable with USB_EHCI_HCD enabled but hang observed even without USB_EHCI_HCD.
>> Maybe related to when high speed interrupts occur in the boot process.
>>
>> - On successful boots following warning is seen
>> [    4.010375] gic_timer_retrigger: lost localtimer interrupt
>>
>> - On successful boots heartbeat LED stops blinking after boot process and left idle. LED can remain stuck in
>> ON state as well. It does blink again when doing activity on console.
>>
>> Workaround:
>>
>> - Disabling CPU_IDLE or even just disabling C3 (MPU OSWR) seems to fix all the above issues.
>>
>> I don't really know what exactly is the issue but it seems to be specific to OMAP4, GIC, MPU OSWR.
>
> I can confirm that disabling CONFIG_CPU_IDLE seems to make the problem
> go away.  Hmm....

Another finger pointing in the same direction: omap2plus_defconfig +
CONFIG_CPU_IDLE=y also fails to boot rather consistently in today's
-next.

Kevin