On 12/11/15 14:37, Lars-Peter Clausen wrote: > On 11/12/2015 03:02 PM, Jon Hunter wrote: > [...] >>>>> One easy way out might be to always call pm_get/pm_but from >>>>> bus_lock,/bus_unlock. This way the chip is guaranteed to be powered up when >>>>> accessed happens. In addition pm_get is called when the IRQ is request and >>>>> pm_put is called when the IRQ is release, this is to ensure the chip stays >>>>> powered when it is actively monitoring the IRQ lines. >>>> >>>> Yes I had thought about that, but it is not quite that easy, because in >>>> the case of request_irq() you don't want to pm_put() after the >>>> bus_unlock(). However, the bus_lock/unlock() are good indicators of >>>> different paths. >>> >>> You'd call pm_get() twice in request_irq() once from bus_lock() and once >>> independently, that way you still have a reference even after the bus_unlock(). >> >> Yes that is a possibility. However, there are places such as >> show_interrupts() (kernel/irq/proc.c) and irq_gc_suspend() that do not >> call bus_lock/unlock() which would need to be handled for PM. May be >> these should also call bus_lock() as well? > > show_interrupts() only accesses software state, not hardware state, or does it? Good point. Today there only appears to be one user: arch/powerpc/sysdev/fsl_msi.c: .irq_print_chip = fsl_msi_print_chip, This one is purely software. However, it would be easy to handle the show_interrupts case if needed. > suspend/resume is a bit tricky. It's kind of driver specific if it needs to > actually access the hardware or whether the state is already shadowed in > software. Maybe we can make this an exception for now and let drivers handle > this on their own. Yes I would agree with you on that. Cheers Jon -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
