Re: [PATCH] serial: omap: Fix missing pm_runtime_resume handling by simplifying code

[Felipe Balbi <balbi@ti.com>]

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On Tue, Mar 25, 2014 at 11:48:47AM -0700, Tony Lindgren wrote:
> The lack of pm_runtime_resume handling for the device state leads into
> device wake-up interrupts not working after a while for runtime PM.
> 
> Also, serial-omap is confused about the use of device_may_wakeup.
> The checks for device_may_wakeup should only be done for suspend and
> resume, not for pm_runtime_suspend and pm_runtime_resume. The wake-up
> events for PM runtime should always be enabled.
> 
> The lack of pm_runtime_resume handling leads into device wake-up
> interrupts not working after a while for runtime PM.
> 
> Rather than try to patch over the issue of adding complex tests to
> the pm_runtime_resume, let's fix the issues properly:
> 
> 1. Make serial_omap_enable_wakeup deal with all internal PM state
>    handling so we don't need to test for up->wakeups_enabled elsewhere.
> 
>    Later on once omap3 boots in device tree only mode we can also
>    remove the up->wakeups_enabled flag and rely on the wake-up
>    interrupt enable/disable state alone.
> 
> 2. Do the device_may_wakeup checks in suspend and resume only,
>    for runtime PM the wake-up events need to be always enabled.
> 
> 3. Finally just call serial_omap_enable_wakeup and make sure we
>    call it also in pm_runtime_resume.
> 
> 4. Note that we also have to use disable_irq_nosync as serial_omap_irq
>    calls pm_runtime_get_sync.
> 
> Fixes: 2a0b965cfb6e (serial: omap: Add support for optional wake-up)
> Cc: stable@vger.kernel.org # v3.13+
> Signed-off-by: Tony Lindgren <tony@atomide.com>
> 
> --- a/drivers/tty/serial/omap-serial.c
> +++ b/drivers/tty/serial/omap-serial.c
> @@ -225,14 +225,19 @@ static inline void serial_omap_enable_wakeirq(struct uart_omap_port *up,
>  	if (enable)
>  		enable_irq(up->wakeirq);
>  	else
> -		disable_irq(up->wakeirq);
> +		disable_irq_nosync(up->wakeirq);

looks to me liket his should be a separate fix of its own...

>  static void serial_omap_enable_wakeup(struct uart_omap_port *up, bool enable)
>  {
>  	struct omap_uart_port_info *pdata = dev_get_platdata(up->dev);
>  
> +	if (enable == up->wakeups_enabled)
> +		return;

is there any case where you would call this function twice with the same
argument ?

> +
>  	serial_omap_enable_wakeirq(up, enable);
> +	up->wakeups_enabled = enable;
> +
>  	if (!pdata || !pdata->enable_wakeup)
>  		return;
>  
> @@ -1495,6 +1500,11 @@ static int serial_omap_suspend(struct device *dev)
>  	uart_suspend_port(&serial_omap_reg, &up->port);
>  	flush_work(&up->qos_work);
>  
> +	if (device_may_wakeup(dev))
> +		serial_omap_enable_wakeup(up, true);
> +	else
> +		serial_omap_enable_wakeup(up, false);
> +
>  	return 0;
>  }
>  
> @@ -1502,6 +1512,9 @@ static int serial_omap_resume(struct device *dev)
>  {
>  	struct uart_omap_port *up = dev_get_drvdata(dev);
>  
> +	if (device_may_wakeup(dev))
> +		serial_omap_enable_wakeup(up, false);
> +
>  	uart_resume_port(&serial_omap_reg, &up->port);
>  
>  	return 0;
> @@ -1877,17 +1890,7 @@ static int serial_omap_runtime_suspend(struct device *dev)
>  
>  	up->context_loss_cnt = serial_omap_get_context_loss_count(up);
>  
> -	if (device_may_wakeup(dev)) {
> -		if (!up->wakeups_enabled) {
> -			serial_omap_enable_wakeup(up, true);
> -			up->wakeups_enabled = true;
> -		}
> -	} else {
> -		if (up->wakeups_enabled) {
> -			serial_omap_enable_wakeup(up, false);
> -			up->wakeups_enabled = false;
> -		}
> -	}
> +	serial_omap_enable_wakeup(up, true);
>  
>  	up->latency = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE;
>  	schedule_work(&up->qos_work);
> @@ -1901,6 +1904,8 @@ static int serial_omap_runtime_resume(struct device *dev)
>  
>  	int loss_cnt = serial_omap_get_context_loss_count(up);
>  
> +	serial_omap_enable_wakeup(up, false);
> +
>  	if (loss_cnt < 0) {
>  		dev_dbg(dev, "serial_omap_get_context_loss_count failed : %d\n",
>  			loss_cnt);

-- 
balbi

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