From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rafal Jaworowski Date: Sat, 31 Mar 2007 19:20:19 +0200 Subject: [U-Boot-Users] [PATCH] icecube/lite5200b: wakeup from low-power support In-Reply-To: <20070315104411.GF22215@moe.telargo.com> References: <20070315103959.GA22215@moe.telargo.com> <20070315104411.GF22215@moe.telargo.com> Message-ID: <460E9853.80902@semihalf.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de 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, 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. 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? - 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) Also, a more general question: isn't time base update required after the wakeup, specially if it's been a long sleep? kind regards, Rafal