"ext Kevin Hilman" <khilman@xxxxxxxxxx> writes: > "Rajendra Nayak" <rnayak@xxxxxx> writes: > >>> "Rajendra Nayak" <rnayak@xxxxxx> writes: >>> >>> > This patch adds the OMAP3 cpuidle driver. Irq enable/disable is done >>> > in the core cpuidle driver before it queries the governor for the >>> > next state. >>> >>> Can you explain why you need the IRQ/FIQ disable added to >>> cpuidle_idle_call() >>> >> >> This was done to prevent any interrupts firing in between a >> cpuidle_curr_governor->select() and target_state->enter(). > > I understand that, but I still don't understand exactly what you're > trying to prevent. Did you have a specific bug that this prevented? > >> An interrupt in between could end up with a previously selected >> state to be programmed. > > Remember that this function _is_ the idle loop, meaning when this runs > nothing else is happening. After the select, if other system activity > has happened (e.g. and interrupt, or thread wakeup etc.), it will run > before the target_state->enter() because of the check for > need_resched(). What happens if this interrupt, or thread wakeup causes change on latency requirements? Then we are entering sleep state which was selected using wrong latency requirement data. > >> Any suggestions on a better way to handle this? > > Just drop the IRQ/FIQ disables altogether. At least these are needed at some point in idle loop. Otherwise we might stepout from idle and sram in a point where it is not acceptable. -- Jouni Högander -- 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
