Re: [PATCH V5 4/9] genirq: Add runtime power management support for IRQ chips

[Jon Hunter <jonathanh@nvidia.com>]

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@nvidia.com>
>>>> Reviewed-by: Kevin Hilman <khilman@baylibre.com>
>>>> Reviewed-by: Marc Zyngier <marc.zyngier@arm.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;
 }
 
Cheers
Jon

-- 
nvpublic