[RFT/PATCH] serial: omap: prevent resume if device is not suspended.
khilman at deeprootsystems.com
Fri Oct 12 16:32:34 EDT 2012
Russell King - ARM Linux <linux at arm.linux.org.uk> writes:
> On Fri, Oct 12, 2012 at 10:59:22AM -0700, Kevin Hilman wrote:
>> Russell King - ARM Linux <linux at arm.linux.org.uk> writes:
>> > On Fri, Oct 12, 2012 at 09:35:54AM -0700, Kevin Hilman wrote:
>> >> Sourav <sourav.poddar at ti.com> writes:
>> >> > diff --git a/drivers/tty/serial/omap-serial.c
>> >> > b/drivers/tty/serial/omap-serial.c
>> >> > index 6ede6fd..3fbc7f7 100644
>> >> > --- a/drivers/tty/serial/omap-serial.c
>> >> > +++ b/drivers/tty/serial/omap-serial.c
>> >> > @@ -1414,6 +1414,7 @@ static int __devinit serial_omap_probe(struct
>> >> > platform_device *pdev)
>> >> > INIT_WORK(&up->qos_work, serial_omap_uart_qos_work);
>> >> >
>> >> > platform_set_drvdata(pdev, up);
>> >> > + pm_runtime_set_active(&pdev->dev);
>> >> NAK.
>> >> This will obviously break platforms where the UARTs are not active
>> >> before driver loads.
>> > I thought I had proposed a solution for this issue, which was this
>> > sequence:
>> > omap_device_enable(dev);
>> > pm_runtime_set_active(dev);
>> > pm_runtime_enable(dev);
>> > Yes, I can understand people not liking the omap_device_enable()
>> > there, but I also notice that the email suggesting that never got a
>> > reply either - not even a "I tried this and it doesn't work" or "it
>> > does work".
>> Yes, that solution would work (though I didn't actually try it.)
>> However, we can't use omap_device_enable() in the driver. We're trying
>> to clean all the drivers of OMAP-specific APIs. That being said,
>> something similar could be done in the device/board init code to ensure
>> the UART HW is in the state that the driver is expecting it, but again,
>> that would just mask the real problem which is that a (re)init of the
>> console UART on 2420/n800 is causing output to disappear.
> See my more expansive suggestion just posted.
> Whatever way, this discrepancy between runtime PM state and actual device
> state is what is biting you, and it is that which needs fixing.
I'm not conviced (yet) that a mismatch is the root cause. Yes, that's
what the author of $SUBJECT patch assumed and stated, but I'm not
If it's an improperly configured mux issue, then the UART will break
whenever the device is actually omap_device_enable'd, whether in the
driver or in the bus layer.
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