On Wed, Dec 21, 2011 at 11:36 AM, Arjan van de Ven <arjan@xxxxxxxxxxxxxxx> wrote: >>> >>> .. or it enters WFI, and a physical device sends it an interrupt, >>> at which point it exits. >> >> None of the cpus will return to the idle loop until all cpus have >> decremented the ready counter back to 0, so they can't wrap around >> again. > > > yikes, so you IPI all the cpus on the first exit. > that must burn power ;-( No, you're not understanding the point of this series. If your cpus can go in and out of idle independently, you don't use this code at all. Each cpu can call WFI and come back out without talking to the other cpu. However, if you have two cpus that share some part of the SoC that can be turned off in idle, like the L2 cache controller or the system bus, the two cpus need to go to idle together, and they will both boot together when either one receives an interrupt (although one will likely immediately go back to a shallower state that doesn't require coordination with the other cpu). There is no way around this, it's how the hardware works on some ARM platforms. -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
