From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <3AF6FC60.D5FE49D9@mvista.com> Date: Mon, 07 May 2001 15:49:52 -0400 From: Dan Malek MIME-Version: 1.0 To: Tania Oka Cc: linuxppc-embedded@lists.linuxppc.org Subject: Re: power saving References: <3AF638AC.659C8A1F@centurysys.co.jp> Content-Type: text/plain; charset=us-ascii Sender: owner-linuxppc-embedded@lists.linuxppc.org List-Id: Tania Oka wrote: > > I would like to reduce power consumption on a custom MPC855T board. This has been asked before, and you can read about it in mailing list archives. Basically, the MPC8xx processors have a dynamic power management system that doesn't gain much from just doing something in the idle() loop. The majority of the power is consumed by peripherals. If they are not enabled, they automatically power down. All of the MPC8xx drivers "do the right thing" on open and close to power up/down peripherals. If you have some very low power standby requirement, you need to add lots of power management software to do things like power down/up any external peripherals on your board, put DRAM in autorefresh mode, shut down the clocks and put the processor into a deep sleep. You could look at some of the PowerMac power management code for design ideas. -- Dan ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/