On Fri, Aug 06, 2010 at 01:30:48PM +0100, Mark Brown wrote: > On Thu, Aug 05, 2010 at 06:01:24PM -0700, david@xxxxxxx wrote: > > On Thu, 5 Aug 2010, Brian Swetland wrote: > > >> Obviously not all clocks are stopped (the DSP and codec are powered > >> and clocked, for example), but yeah we can clock gate and power gate > >> the cpu and most other peripherals while audio is playing on a number > >> of ARM SoC designs available today (and the past few years). > > > does this then mean that you have multiple variations of suspend? > > > for example, one where the audio stuff is left powered, and one where it > > isn't? > > This was the core of the issue I was raising in the last thread about > this (the one following the rename to suspend blockers). Essentially > what happens in a mainline context is that some subsystems can with > varying degress of optionality ignore some or all of the instruction to > suspend and keep bits of the system alive during suspend. > > Those that stay alive will either have per subsystem handling or will be > outside the direct control of the kernel entirely (the modem is a good > example of the latter case in many systems - in terms of the software > it's essentially a parallel computer that's sitting in the system rather > than a perhiperal of the AP). This underscores a basic difference between servers and these embedded devices. When you suspend a server, it is doing nothing, because servers rely very heavily on the CPUs. In contrast, many embedded devices can perform useful work even when the CPUs are completely powered down. Thanx, Paul _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
