Re: [PATCH 1/2] genirq: add chip_{suspend,resume} PM support to irq_chip

[Thomas Gleixner <tglx@linutronix.de>]

On Tue, 21 Jul 2015, Florian Fainelli wrote:
> On 20/06/15 07:11, Thomas Gleixner wrote:
> > On Fri, 19 Jun 2015, Brian Norris wrote:
> >> This patch adds a second set of suspend/resume hooks to irq_chip, this
> >> time to represent *chip* suspend/resume, rather than IRQ suspend/resume.
> >> These callbacks will always be called for an irqchip and are based on
> >> the per-chip irq_chip_generic struct, rather than the per-IRQ irq_data
> >> struct.
> > 
> > There is no per-chip irq_chip_generic struct. It's only there if the
> > irq chip has been instantiated as a generic chip.
> >  
> >>  /**
> >>   * struct irq_chip - hardware interrupt chip descriptor
> >>   *
> >> @@ -317,6 +319,12 @@ static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d)
> >>   * @irq_suspend:	function called from core code on suspend once per chip
> >>   * @irq_resume:		function called from core code on resume once per chip
> >>   * @irq_pm_shutdown:	function called from core code on shutdown once per chip
> >> + * @chip_suspend:	function called from core code on suspend once per
> >> + *			chip; for handling chip details even when no interrupts
> >> + *			are in use
> >> + * @chip_resume:	function called from core code on resume once per chip;
> >> + *			for handling chip details even when no interrupts are
> >> + *			in use
> >>   * @irq_calc_mask:	Optional function to set irq_data.mask for special cases
> >>   * @irq_print_chip:	optional to print special chip info in show_interrupts
> >>   * @irq_request_resources:	optional to request resources before calling
> >> @@ -357,6 +365,8 @@ struct irq_chip {
> >>  	void		(*irq_suspend)(struct irq_data *data);
> >>  	void		(*irq_resume)(struct irq_data *data);
> >>  	void		(*irq_pm_shutdown)(struct irq_data *data);
> >> +	void		(*chip_suspend)(struct irq_chip_generic *gc);
> >> +	void		(*chip_resume)(struct irq_chip_generic *gc);
> > 
> > I really don't want to set a precedent for random (*foo)(*bar)
> > callbacks.
> >  
> >> +
> >> +		if (ct->chip.chip_suspend)
> >> +			ct->chip.chip_suspend(gc);
> > 
> > So wouldn't it be the more intuitive solution to make this a callback
> > in the struct gc itself?
> 
> Brian can correct me, but his approach is more generic, if there is
> another irqchip driver needing a similar infrastructure, this would be
> already there, and directly usable.

No it's not directly usable. It's only usable with irq_chip_generic
incarnations.

> Maybe all we need to is to change the chip_suspend/resume arguments
> to pass a reference to irq_chip instead?

I just read back on the problem report which was mentioned in the
changelog:

"It's not a problem with patch 7, exactly, it's a problem with the
 irqchip driver which handles the UART interrupt mask (irq-bcm7120-l2.c).
 The problem is that with a trimmed down device tree (such as the one
 found at arch/arm/boot/dts/bcm7445-bcm97445svmb.dtb), none of the child
 interrupts of the 'irq0_intc' node are described -- we don't have device
 tree nodes for them yet -- but we still require saving and restoring the
 forwarding mask (see 'brcm,int-fwd-mask') in order for the UART
 interrupts to continue operating."

So you are trying to work around a flaw in the device tree by adding
random callbacks to the core kernel?

Thanks,

	tglx