Hi Rafael,

On Wed, Jan 18, 2012 at 4:08 PM, Rafael J. Wysocki [off-list ref] wrote:

On Wednesday, January 18, 2012, Simon Glass wrote:

quoted

[+cc Rafael J. Wysocki [off-list ref] who I think wrote the wakeup.c code]

Hi Alan, Paul,

On Tue, Jan 17, 2012 at 8:17 PM, Paul E. McKenney
[off-list ref] wrote:

quoted

On Tue, Jan 17, 2012 at 08:10:36PM +0000, Alan Cox wrote:

quoted

On Tue, 17 Jan 2012 10:56:03 -0800
Simon Glass [off-list ref] wrote:

quoted

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.

quoted

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.

Ok, that makes sense - thank you for clearing it up. I will do a new patch.

Regards
Simon

Thanks,
Rafael

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