On Wednesday, January 18, 2012, Simon Glass wrote: > [+cc Rafael J. Wysocki <rjw@xxxxxxx> who I think wrote the wakeup.c code] > > Hi Alan, Paul, > > On Tue, Jan 17, 2012 at 8:17 PM, Paul E. McKenney > <paulmck@xxxxxxxxxxxxxxxxxx> wrote: > > On Tue, Jan 17, 2012 at 08:10:36PM +0000, Alan Cox wrote: > >> On Tue, 17 Jan 2012 10:56:03 -0800 > >> Simon Glass <sjg@xxxxxxxxxxxx> wrote: > >> > >> > Since serial_core now does not make serial ports wake-up capable by > >> > default, add a parameter to support this feature in the 8250 UART. > >> > This is the only UART where I think this feature is useful. > >> > >> NAK > >> > >> Things should just work for users. Magic parameters is not an > >> improvement. If its a performance problem someone needs to fix the rcu > >> sync overhead or stop using rcu on that path. > > OK fair enough, I agree. Every level I move down the source tree > affects more people though. > > > > > I must say that I lack context here, even after looking at the patch, > > but the synchronize_rcu_expedited() primitives can be used if the latency > > of synchronize_rcu() is too large. > > > > Let me provide a bit of context. The serial_core code seems to be the > only place in the kernel that does this: > > device_init_wakeup(tty_dev, 1); > device_set_wakeup_enable(tty_dev, 0); It shouldn't do that. It should just do device_set_wakeup_capable(tty_dev, true) instead. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
