linux-kernel - Re: [PATCH 08/15] genirq: Add runtime power management support for IRQ chips

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Message-ID: <56EAC98A.7090405@nvidia.com>
Date:	Thu, 17 Mar 2016 15:13:14 +0000
From:	Jon Hunter <jonathanh@...dia.com>
To:	Marc Zyngier <marc.zyngier@....com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jason Cooper <jason@...edaemon.net>,
	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>,
	Linus Walleij <linus.walleij@...aro.org>
CC:	Kevin Hilman <khilman@...nel.org>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Grygorii Strashko <grygorii.strashko@...com>,
	Lars-Peter Clausen <lars@...afoo.de>,
	<linux-tegra@...r.kernel.org>, <linux-omap@...r.kernel.org>,
	<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 08/15] genirq: Add runtime power management support for
 IRQ chips

Hi Marc,

On 17/03/16 15:02, Marc Zyngier wrote:
> Hi Jon,
> 
> On 17/03/16 14:19, Jon Hunter wrote:
>> Some IRQ chips may be located in a power domain outside of the CPU
>> subsystem and hence will require device specific runtime power
>> management. In order to support such IRQ chips, add a pointer for a
>> device structure to the irq_chip structure, and if this pointer is
>> populated by the IRQ chip driver and CONFIG_PM is selected in the kernel
>> configuration, then the pm_runtime_get/put APIs for this chip will be
>> called when an IRQ is requested/freed, respectively.
>>
>> When entering system suspend and each interrupt is disabled if there is
>> no wake-up set for that interrupt. For an IRQ chip that utilises runtime
>> power management, print a warning message for each active interrupt that
>> has no wake-up set because these interrupts may be unnecessarily keeping
>> the IRQ chip enabled during system suspend.
>>
>> Signed-off-by: Jon Hunter <jonathanh@...dia.com>
>> ---
>>  include/linux/irq.h    |  5 +++++
>>  kernel/irq/chip.c      | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++
>>  kernel/irq/internals.h |  1 +
>>  kernel/irq/manage.c    | 14 +++++++++++---
>>  kernel/irq/pm.c        |  3 +++
>>  5 files changed, 72 insertions(+), 3 deletions(-)
>>
>> diff --git a/include/linux/irq.h b/include/linux/irq.h
>> index c4de62348ff2..82f36390048d 100644
>> --- a/include/linux/irq.h
>> +++ b/include/linux/irq.h
>> @@ -315,6 +315,7 @@ static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d)
>>  /**
>>   * struct irq_chip - hardware interrupt chip descriptor
>>   *
>> + * @parent:		pointer to associated device
>>   * @name:		name for /proc/interrupts
>>   * @irq_startup:	start up the interrupt (defaults to ->enable if NULL)
>>   * @irq_shutdown:	shut down the interrupt (defaults to ->disable if NULL)
>> @@ -354,6 +355,7 @@ static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d)
>>   * @flags:		chip specific flags
>>   */
>>  struct irq_chip {
>> +	struct device	*parent;
> 
> Nit: Please don't call this just "parent". We have parent fields in
> irq_data and irq_domain structures, and they always are a pointer to the
> same type, indicating some form of stacking. Here, we're pointing to a
> different type altogether...
> 
> How about calling it "dev", or "device" instead? It would make it much
> clearer that when crossing that pointer, we're in another subsystem
> altogether.

I will defer to Linus W here, as it was his request we make this
'parent' and not 'dev'. See ...

http://marc.info/?l=linux-kernel&m=145035839623442&w=2

> I'll come back to the rest of the patch a bit later, but I wanted to put
> that one out right away... ;-)

Thanks,
Jon