linux-kernel - Re: [Patch v4] x86, irq, PCI: Keep IRQ assignment for runtime power management

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Message-ID: <54013AA8.8050200@linux.intel.com>
Date:	Sat, 30 Aug 2014 10:44:56 +0800
From:	Jiang Liu <jiang.liu@...ux.intel.com>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	"Rafael J. Wysocki" <rafael@...nel.org>
CC:	EmanueL Czirai <amanual@...nmailbox.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Randy Dunlap <rdunlap@...radead.org>,
	Yinghai Lu <yinghai@...nel.org>,
	Borislav Petkov <bp@...en8.de>,
	Grant Likely <grant.likely@...aro.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Tony Luck <tony.luck@...el.com>,
	Joerg Roedel <joro@...tes.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	x86@...nel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linux PCI <linux-pci@...r.kernel.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>
Subject: Re: [Patch v4] x86, irq, PCI: Keep IRQ assignment for runtime power
 management



On 2014/8/30 7:24, Rafael J. Wysocki wrote:
> On Friday, August 29, 2014 04:42:34 PM Rafael J. Wysocki wrote:
>> On Fri, Aug 29, 2014 at 11:26 AM, Jiang Liu <jiang.liu@...ux.intel.com> wrote:
>>> Now IOAPIC driver dynamically allocates IRQ numbers for IOAPIC pins.
>>> We need to keep IRQ assignment for PCI devices during runtime power
>>> management, otherwise it may cause failure of device wakeups.
>>>
>>> Commit 3eec595235c17a7 "x86, irq, PCI: Keep IRQ assignment for PCI
>>> devices during suspend/hibernation" has fixed the issue for suspend/
>>> hibernation, we also need the same fix for runtime device sleep too.
>>>
>>> Fix: https://bugzilla.kernel.org/show_bug.cgi?id=83271
>>> Reported-and-Tested-by: EmanueL Czirai <amanual@...nmailbox.org>
>>> Signed-off-by: Jiang Liu <jiang.liu@...ux.intel.com>
>>> ---
>>>  arch/x86/include/asm/io_apic.h |    2 ++
>>>  arch/x86/kernel/apic/io_apic.c |   12 ++++++++++++
>>>  arch/x86/pci/intel_mid_pci.c   |    2 +-
>>>  arch/x86/pci/irq.c             |    2 +-
>>>  drivers/acpi/pci_irq.c         |    4 ++++
>>>  5 files changed, 20 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/arch/x86/include/asm/io_apic.h b/arch/x86/include/asm/io_apic.h
>>> index 0aeed5ca356e..478c490f3654 100644
>>> --- a/arch/x86/include/asm/io_apic.h
>>> +++ b/arch/x86/include/asm/io_apic.h
>>> @@ -227,6 +227,8 @@ static inline void io_apic_modify(unsigned int apic, unsigned int reg, unsigned
>>>
>>>  extern void io_apic_eoi(unsigned int apic, unsigned int vector);
>>>
>>> +extern bool mp_should_keep_irq(struct device *dev);
>>> +
>>>  #else  /* !CONFIG_X86_IO_APIC */
>>>
>>>  #define io_apic_assign_pci_irqs 0
>>> diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
>>> index 29290f554e79..1e9a921d9701 100644
>>> --- a/arch/x86/kernel/apic/io_apic.c
>>> +++ b/arch/x86/kernel/apic/io_apic.c
>>> @@ -3946,6 +3946,18 @@ int mp_set_gsi_attr(u32 gsi, int trigger, int polarity, int node)
>>>         return ret;
>>>  }
>>>
>>> +bool mp_should_keep_irq(struct device *dev)
>>> +{
>>> +       if (dev->power.is_prepared)
>>> +               return true;
>>> +#ifdef CONFIG_PM_RUNTIME
>>> +       if (dev->power.runtime_status == RPM_SUSPENDING)
>>> +               return true;
>>> +#endif
>>
>> No, you can't do that.  It is racy and incorrect.
> 
> Well, maybe not.
> 
>> Please give me some time for looking into this.
> 
> So I guess the intended check is "Am I running in a suspend callback"?
Hi Rafael,
	Yes, we are trying to check whether it's called for suspend.
Function pci_disable_device() may be called when:
1) unbinding PCI driver
2) destroying PCI device
3) suspending for runtime power management or sleep
For case 1 and 2, we should release IRQ assigned. But we need to
keep assigned IRQ for case 3.

So is it safe to check runtime_status and is_prepared flags to detect
case 3? Any better ways?

Regards!
Gerry


> 
> Rafael
> 
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