[ Gah, saw it didn't make it to u-boot ML, resending ]
On 31/03/07 19:20 +0200, Rafal Jaworowski wrote:
Domen Puncer wrote:
U-Boot part of Lite5200b low power mode support. Puts SDRAM out of self-refresh and transfers control to address saved at physical 0x0.
Hi Domen,
Hi!
As I understand while waking up from the low-power mode the machine is effectively powering on, similarly to the cold reset, so U-Boot runs from the beginning as usual, but after the SDRAM controller has been initialised we detect the wakeup and teleport to the saved DRAM address.
Right.
Since in case of a wakeup from the low-power mode we skip everything in U-Boot that is happening past initdram(), please clarify the following:
- are you sure there are no steps beyond init_func_ram()/board_init_f()
that should be performed while waking up? For example:
- are all timers settings properly re-stored?
Hmm... right, I forgot to restart watchdog... but that will be done in Linux code.
- wouldn't the host/PCI bridge need to be re-initialised and
re-configured as part of the wakeup process? Did you happen to test some PCI devices and would they survive after wakeup from the the low-power mode? (A similar question would apply to the USB controller)
Honestly, I don't know for PCI. IIRC some time ago, kernel compiled with CONFIG_PCI didn't boot for me.
USB controller/devices survived the wakeup last time I checked.
Also, a more general question: isn't time base update required after the wakeup, specially if it's been a long sleep?
Lite5200b doesn't have an external time source.
Thanks!
Domen