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Date: Mon, 6 Jun 2016 17:08:26 +0100
From: Marc Zyngier <marc.zyngier@....com>
To: Jon Hunter <jonathanh@...dia.com>,
Grygorii Strashko <grygorii.strashko@...com>,
Thomas Gleixner <tglx@...utronix.de>,
Jason Cooper <jason@...edaemon.net>,
Kevin Hilman <khilman@...nel.org>
Cc: 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>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
Lars-Peter Clausen <lars@...afoo.de>,
Linus Walleij <linus.walleij@...aro.org>,
linux-tegra@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH V5 4/9] genirq: Add runtime power management support for
IRQ chips
On 06/06/16 16:06, Jon Hunter wrote:
>
> On 06/06/16 15:36, Grygorii Strashko wrote:
>> On 06/06/2016 05:30 PM, Jon Hunter wrote:
>>>
>>> On 06/06/16 15:13, Grygorii Strashko wrote:
>>>> On 06/06/2016 02:53 PM, 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.
>>>>>
>>>>> Signed-off-by: Jon Hunter <jonathanh@...dia.com>
>>>>> Reviewed-by: Kevin Hilman <khilman@...libre.com>
>>>>> Reviewed-by: Marc Zyngier <marc.zyngier@....com>
>>>>> ---
>>>>> include/linux/irq.h | 4 ++++
>>>>> kernel/irq/chip.c | 35 +++++++++++++++++++++++++++++++++++
>>>>> kernel/irq/internals.h | 1 +
>>>>> kernel/irq/manage.c | 31 ++++++++++++++++++++++++++++++-
>>>>> 4 files changed, 70 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/include/linux/irq.h b/include/linux/irq.h
>>>>> index 4d758a7c604a..6c92a847394d 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_device: pointer to parent device for irqchip
>>>>> * @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_device;
>>>>> const char *name;
>>>>> unsigned int (*irq_startup)(struct irq_data *data);
>>>>> void (*irq_shutdown)(struct irq_data *data);
>>>>> @@ -488,6 +490,8 @@ extern void handle_bad_irq(struct irq_desc *desc);
>>>>> extern void handle_nested_irq(unsigned int irq);
>>>>>
>>>>> extern int irq_chip_compose_msi_msg(struct irq_data *data, struct msi_msg *msg);
>>>>> +extern int irq_chip_pm_get(struct irq_data *data);
>>>>> +extern int irq_chip_pm_put(struct irq_data *data);
>>>>> #ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
>>>>> extern void irq_chip_enable_parent(struct irq_data *data);
>>>>> extern void irq_chip_disable_parent(struct irq_data *data);
>>>>> diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
>>>>> index 2f9f2b0e79f2..b09226e895c7 100644
>>>>> --- a/kernel/irq/chip.c
>>>>> +++ b/kernel/irq/chip.c
>>>>> @@ -1093,3 +1093,38 @@ int irq_chip_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
>>>>>
>>>>> return 0;
>>>>> }
>>>>> +
>>>>> +/**
>>>>> + * irq_chip_pm_get - Enable power for an IRQ chip
>>>>> + * @data: Pointer to interrupt specific data
>>>>> + *
>>>>> + * Enable the power to the IRQ chip referenced by the interrupt data
>>>>> + * structure.
>>>>> + */
>>>>> +int irq_chip_pm_get(struct irq_data *data)
>>>>> +{
>>>>> + int retval = 0;
>>>>> +
>>>>> + if (IS_ENABLED(CONFIG_PM) && data->chip->parent_device)
>>>>> + retval = pm_runtime_get_sync(data->chip->parent_device);
>>>>
>>>> Sry, for the late comment - above require pm_runtime_put_noidle(data->chip->parent_device);
>>>> in case of failure.
>>>
>>> No problem. Sorry, can you elaborate? I am not familiar with the
>>> _put_noidle().
>>>
>>
>> Question here in use counter - pm_runtime_get_sync() will increment usage_count
>> always and it will not decrement it in case of failure.
>> pm_runtime_put_noidle() expected to restore usage_count state (-1).
>
> Thanks was not aware of that.
>
> Kevin, Marc, given that you have reviewed this one, are you ok with the
> above change Grygorii is proposing?
>
> diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
> index b09226e895c7..63f1860acc4c 100644
> --- a/kernel/irq/chip.c
> +++ b/kernel/irq/chip.c
> @@ -1105,8 +1105,11 @@ int irq_chip_pm_get(struct irq_data *data)
> {
> int retval = 0;
>
> - if (IS_ENABLED(CONFIG_PM) && data->chip->parent_device)
> + if (IS_ENABLED(CONFIG_PM) && data->chip->parent_device) {
> retval = pm_runtime_get_sync(data->chip->parent_device);
> + if (retval < 0)
> + pm_runtime_put_noidle(data->chip->parent_device);
> + }
>
> return (retval < 0) ? retval : 0;
> }
>
That looks correct to me (having had a look at
Documentation/power/runtime_pm.txt).
M.
--
Jazz is not dead. It just smells funny...
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