Subject: [PATCH] ARM: OMAP2: UART: fix console UART mismatched runtime PM status

From: [email-masked] (Kevin Hilman)
Date: Tue, 16 Oct 2012 18:03:39 -0700

Tony Lindgren <[email-masked]> writes:

> * Felipe Balbi <[email-masked]> [121016 03:32]:
>> Hi,
>> 
>> On Mon, Oct 15, 2012 at 04:49:58PM -0700, Kevin Hilman wrote:
>> > From: Kevin Hilman <[email-masked]>
>> > 
>> > The runtime PM framework assumes that the hardware state of devices
>> > when initialized is disabled.  For all omap_devices, we idle/disable
>> > device by default.  However, the console uart uses a "no idle" option
>> > during omap_device init in order to allow earlyprintk usage to work
>> > seamlessly during boot.
>> > 
>> > Because the hardware is left partially enabled after init (whatever
>> > the bootloader settings were), the omap_device should later be fully
>> > initialized (including mux) and the runtime PM framework should be
>> > told that the device is active, and not disabled so that the hardware
>> > state is in sync with runtime PM state.
>> > 
>> > To fix, after the device has been created/registered, call
>> > omap_device_enable() to finialize init and use pm_runtime_set_active()
>> > to tell the runtime PM core the device is enabled.
>> > 
>> > Tested on 2420/n810, 3530/Overo, 3530/Beagle, 3730/OveroSTORM,
>> > 3730/Beagle-xM, 4460/PandaES.
>> > 
>> > Reported-by: Paul Walmsley <[email-masked]>
>> > Suggested-by: Russell King <[email-masked]>
>> > Cc: Felipe Balbi <[email-masked]>
>> > Cc: Sourav Poddar <[email-masked]>
>> > Signed-off-by: Kevin Hilman <[email-masked]>
>> > ---
>> > Applies against v3.7-rc1.
>> > Fix targetted for v3.7.
>> > 
>> > I'm still not entirely sure why this has worked up to now on OMAP3/4
>> > but not on OMAP2.  Even so, this fix is needed for all platforms to
>> > ensure matching hardware state and runtime PM state.
>> > 
>> >  arch/arm/mach-omap2/serial.c |    5 +++++
>> >  1 file changed, 5 insertions(+)
>> > 
>> > diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c
>> > index 0405c81..37b5dbe 100644
>> > --- a/arch/arm/mach-omap2/serial.c
>> > +++ b/arch/arm/mach-omap2/serial.c
>> > @@ -327,6 +327,11 @@ void __init omap_serial_init_port(struct omap_board_data *bdata,
>> >  	if ((console_uart_id == bdata->id) && no_console_suspend)
>> >  		omap_device_disable_idle_on_suspend(pdev);
>> >  
>> > +	if (console_uart_id == bdata->id) {
>> > +		omap_device_enable(pdev);
>> > +		pm_runtime_set_active(&pdev->dev);
>> > +	}
>> > +
>> >  	oh->mux = omap_hwmod_mux_init(bdata->pads, bdata->pads_cnt);
>> >  
>> >  	oh->dev_attr = uart;
>> 
>> looks good to me. Even took care of doing that only for the console
>> UART.
>
> Applying into omap-for-v3.7-rc1/fixes-take3.
>

Doh, this isn't quite right yet.  Some more PM testing shows that UART
wakeups are broken, so this isn't ready for v3.7 yet.

To be continued...

Kevin