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Date: Wed, 9 Jul 2014 23:28:12 -0700 From: Tony Lindgren <tony@...mide.com> To: Sebastian Andrzej Siewior <bigeasy@...utronix.de> Cc: linux-omap@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, Felipe Balbi <balbi@...com>, linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org, mika.westerberg@...ux.intel.com Subject: Re: [PATCH 3/6] tty: serial: 8250 core: add runtime pm * Sebastian Andrzej Siewior <bigeasy@...utronix.de> [140709 10:52]: > While comparing the OMAP-serial and the 8250 part of this I noticed that > the the latter does not use runtime-pm. Here are the pieces. It is > basically a get before first register access and a last_busy + put after > last access. > If I understand this correct, it should do nothing as long as > pm_runtime_use_autosuspend() + pm_runtime_enable() isn't invoked on the > device. ... > --- a/drivers/tty/serial/8250/8250_core.c > +++ b/drivers/tty/serial/8250/8250_core.c > @@ -571,7 +573,17 @@ static void serial8250_set_sleep(struct uart_8250_port *p, int sleep) > serial_out(p, UART_EFR, 0); > serial_out(p, UART_LCR, 0); > } > + > + if (!device_may_wakeup(p->port.dev)) { > + if (sleep) > + pm_runtime_forbid(p->port.dev); > + else > + pm_runtime_allow(p->port.dev); > + } > } > +out: > + pm_runtime_mark_last_busy(p->port.dev); > + pm_runtime_put_autosuspend(p->port.dev); > } The device_may_wakeup logic here is wrong as I described in the earlier thread. For runtime PM, the wake-up events should be always enabled. So the device_may_wakeup checks should be only done for suspend and resume. Regards, Tony -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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