On Tue, 20 Mar 2007, David Brownell wrote: > On Tuesday 20 March 2007 4:06 am, Johannes Berg wrote: > > Almost all users of pm_ops only support mem sleep, don't check in .valid > > and don't reject any others in .prepare so users can be confused if they > > check /sys/power/state, especially when new states are ever added. > > By the way ... as a note to implementors, it should be trivial to > implement a basic "standby" state that suspends drivers, disables > many clocks, and probably puts DRAM into self-refresh mode, but > uses only the wait-for-interrupt CPU lowpower mode. > > A key difference between that and STR would then be that STR does > extra magic, like switching the CPU to a slow clock and then turning > off all the clocks that drive the chip "fast". Also, that because > it disables so many clocks, the SOC probably can't support as many > types of wakeup events in STR. Hm, interesting. What you described above is very similar to what I've just implemented for a 8241 based system (linkstation: http://ozlabs.org/pipermail/linuxppc-dev/2007-March/thread.html#33203). But Paul Mackerras suggested to consider it a StR, whereas Johannes Berg proposed to call it a standby, which is also what seems to be more logical to me. May we agree on some "simple" criteria, like "CPU power on, i.e., CPU registers preserved"? If yes - standby, CPU off, registers lost - StR? I can imagine CPUs with multiple power sources allowing to switch some of them on and off respectively losing / keeping some register sets... Thanks Guennadi --- Guennadi Liakhovetski _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
