[4.4-rc][PATCH] genirq / PM: restore system wake up from chained interrupts

[Mika Westerberg]

On Tue, Nov 10, 2015 at 11:58:12AM +0200, Grygorii Strashko wrote:
> Commit e509bd7da149 ("genirq: Allow migration of chained interrupts
> by installing default action") breaks PCS wake up IRQ behaviour on
> TI OMAP based platforms (dra7-evm).
> 
> TI OMAP IRQ wake up configuration:
> GIC-irqchip->PCM_IRQ
>   |- omap_prcm_register_chain_handler
>      |- PRCM-irqchip -> PRCM_IO_IRQ
>         |- pcs_irq_chain_handler
>            |- pinctrl-irqchip -> PCS_uart1_wakeup_irq
> 
> This happens because IRQ PM code (irq/pm.c) is expected to ignore
> chained interrupts by default:
>   static bool suspend_device_irq(struct irq_desc *desc)
>   {
> 	if (!desc->action || desc->no_suspend_depth)
> 		return false;
>  - it's expected !desc->action = true for chained interrupts;

Indeed it is. I missed that, sorry.

> but, after above change, all chained interrupt descriptors will
> have default action handler installed - chained_action.
> As result, chained interrupts will be silently disabled during system
> suspend.
> 
> Hence, fix it by introducing helper function irq_desc_is_chained() and
> use it in suspend_device_irq() for chained interrupts identification
> and skip them, once detected.
> 
> Cc: Mika Westerberg <mika.westerberg at linux.intel.com>

FWIW,

Reviewed-by: Mika Westerberg <mika.westerberg at linux.intel.com>