linux-kernel - Re: [PATCH V2 06/14] irqdomain: Don't set type when mapping an IRQ

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Date:	Thu, 21 Apr 2016 16:45:23 +0100
From:	Jon Hunter <jonathanh@...dia.com>
To:	Thomas Gleixner <tglx@...utronix.de>,
	Jason Cooper <jason@...edaemon.net>,
	Marc Zyngier <marc.zyngier@....com>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Stephen Warren <swarren@...dotorg.org>,
	Thierry Reding <thierry.reding@...il.com>
CC:	Kevin Hilman <khilman@...nel.org>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Grygorii Strashko <grygorii.strashko@...com>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Linus Walleij <linus.walleij@...aro.org>,
	<linux-tegra@...r.kernel.org>, <linux-omap@...r.kernel.org>,
	<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V2 06/14] irqdomain: Don't set type when mapping an IRQ


On 20/04/16 12:03, Jon Hunter wrote:
> Some IRQ chips, such as GPIO controllers or secondary level interrupt
> controllers, may require require additional runtime power management
> control to ensure they are accessible. For such IRQ chips, it makes sense
> to enable the IRQ chip when interrupts are requested and disabled them
> again once all interrupts have been freed.
> 
> When mapping an IRQ, the IRQ type settings are read and then programmed.
> The mapping of the IRQ happens before the IRQ is requested and so the
> programming of the type settings occurs before the IRQ is requested. This
> is a problem for IRQ chips that require additional power management
> control because they may not be accessible yet. Therefore, when mapping
> the IRQ, don't program the type settings, just save them and then program
> these saved settings when the IRQ is requested (so long as if they are not
> overridden via the call to request the IRQ).
> 
> Add a stub function for irq_domain_free_irqs() to avoid any compilation
> errors when CONFIG_IRQ_DOMAIN_HIERARCHY is not selected.
> 
> Signed-off-by: Jon Hunter <jonathanh@...dia.com>
> ---
>  include/linux/irqdomain.h |  3 +++
>  kernel/irq/irqdomain.c    | 17 +++++++++++++----
>  2 files changed, 16 insertions(+), 4 deletions(-)

[snip]
 
> -	/* Set type if specified and different than the current one */
> -	if (type != IRQ_TYPE_NONE &&
> -	    type != irq_get_trigger_type(virq))
> -		irq_set_irq_type(virq, type);
> +	irq_data = irq_get_irq_data(virq);
> +	if (!irq_data) {
> +		if (irq_domain_is_hierarchy(domain))
> +			irq_domain_free_irqs(virq, 1);
> +		else
> +			irq_dispose_mapping(virq);
> +		return 0;
> +	}
> +
> +	/* Store trigger type */
> +	irqd_set_trigger_type(irq_data, type);
> +

I appear to have missed another place for saving the irq type
which I had change in this version. Next time I will triple
check! Should have been ...


diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h
index 2aed04396210..fc66876d1965 100644
--- a/include/linux/irqdomain.h
+++ b/include/linux/irqdomain.h
@@ -440,6 +440,9 @@ static inline int irq_domain_alloc_irqs(struct irq_domain *domain,
        return -1;
 }
 
+static inline void irq_domain_free_irqs(unsigned int virq,
+                                       unsigned int nr_irqs) { }
+
 static inline bool irq_domain_is_hierarchy(struct irq_domain *domain)
 {
        return false;
diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index 3d6ef5527b71..46ecf5d468b2 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -569,6 +569,7 @@ static void of_phandle_args_to_fwspec(struct of_phandle_args *irq_data,
 unsigned int irq_create_fwspec_mapping(struct irq_fwspec *fwspec)
 {
        struct irq_domain *domain;
+       struct irq_data *irq_data;
        irq_hw_number_t hwirq;
        unsigned int type = IRQ_TYPE_NONE;
        int virq;
@@ -619,7 +620,11 @@ unsigned int irq_create_fwspec_mapping(struct irq_fwspec *fwspec)
                 * it now and return the interrupt number.
                 */
                if (IRQ_TYPE_NONE == irq_get_trigger_type(virq)) {
-                       irq_set_irq_type(virq, type);
+                       irq_data = irq_get_irq_data(virq);
+                       if (!irq_data)
+                               return 0;
+
+                       irqd_set_trigger_type(irq_data, type);
                        return virq;
                }
 
@@ -639,10 +644,18 @@ unsigned int irq_create_fwspec_mapping(struct irq_fwspec *fwspec)
                        return virq;
        }
 
-       /* Set type if specified and different than the current one */
-       if (type != IRQ_TYPE_NONE &&
-           type != irq_get_trigger_type(virq))
-               irq_set_irq_type(virq, type);
+       irq_data = irq_get_irq_data(virq);
+       if (!irq_data) {
+               if (irq_domain_is_hierarchy(domain))
+                       irq_domain_free_irqs(virq, 1);
+               else
+                       irq_dispose_mapping(virq);
+               return 0;
+       }
+
+       /* Store trigger type */
+       irqd_set_trigger_type(irq_data, type);
+
        return virq;
 }
 EXPORT_SYMBOL_GPL(irq_create_fwspec_mapping);