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

From: [email-masked] (Roger Quadros)
Date: Thu, 8 May 2014 15:53:24 +0300

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

- 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.

cheers,
-roger