linux-kernel - Re: [PATCH 07/15] irqdomain: Don't set type when mapping an IRQ

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Message-ID: <56EAF525.9000305@nvidia.com>
Date:	Thu, 17 Mar 2016 18:19:17 +0000
From:	Jon Hunter <jonathanh@...dia.com>
To:	Thomas Gleixner <tglx@...utronix.de>,
	Jason Cooper <jason@...edaemon.net>,
	Marc Zyngier <marc.zyngier@....com>,
	Benoît Cousson <bcousson@...libre.com>,
	Tony Lindgren <tony@...mide.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 07/15] irqdomain: Don't set type when mapping an IRQ


On 17/03/16 14:19, 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    | 18 ++++++++++++++----
>  kernel/irq/manage.c       |  7 +++++++
>  3 files changed, 24 insertions(+), 4 deletions(-)
> 
> 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 0ea285baa619..332bee2205e0 100644
> --- a/kernel/irq/irqdomain.c
> +++ b/kernel/irq/irqdomain.c
> @@ -576,6 +576,7 @@ 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 cur_type = IRQ_TYPE_NONE;
>  	unsigned int type = IRQ_TYPE_NONE;
> @@ -638,10 +639,19 @@ unsigned int irq_create_fwspec_mapping(struct irq_fwspec *fwspec)
>  		return 0;
>  	}
>  
> -	/* 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;
> +	}

I should only free/dispose here if we actually created it! Will fix this
as well :-(

Jon