linux-kernel - Re: [PATCH linux-next v2] arm64: PCI: Introduce pcibios_free

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Date:   Wed, 22 Sep 2021 02:49:13 +0000
From:   yajun.deng@...ux.dev
To:     "Lorenzo Pieralisi" <lorenzo.pieralisi@....com>
Cc:     catalin.marinas@....com, will@...nel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH linux-next v2] arm64: PCI: Introduce
 pcibios_free_irq() helper function

September 21, 2021 11:47 PM, "Lorenzo Pieralisi" <lorenzo.pieralisi@....com> wrote:

> On Thu, Aug 26, 2021 at 02:04:06PM +0800, Yajun Deng wrote:
> 
>> pcibios_alloc_irq() will be called in pci_device_probe(), but there
>> hasn't pcibios_free_irq() in arm64 architecture correspond it.
>> pcibios_free_irq() is an empty weak function in drivers/pci/pci-driver.c.
> 
> "pcibios_alloc_irq() is a weak function called to allocate IRQs for
> a device in pci_device_probe(); arm64 implements it with
> ACPI specific code to enable IRQs for a device.
> 
> When a device is removed (pci_device_remove()) the pcibios_free_irq()
> counterpart is called.
> 
> Current arm64 code does not implement a pcibios_free_irq() function,
> and therefore, the weak empty stub is executed, which means that the
> IRQ for a device are not properly disabled when a device is removed.
> 
> Add an arm64 pcibios_free_irq() to undo the actions carried out in
> pcibios_alloc_irq()."
> 
> This is a stub commit log. Then you need to describe the bug you
> are fixing (if any, or it is just code inspection ?)
> 
It is just code inspection.
>> So add pcibios_free_irq() for correspond it. This will be called
>> in pci_device_remove().
>> 
>> ====================
>> v2: remove the change in pcibios_alloc_irq(), and modify the commit log.
>> ====================
> 
> Don't add versioning in the commit log, it does not belong here.
> 
> I don't think we should send this to stable kernels straight away,
> it is best to make sure we are not triggering any regressions first.
> 
> Lorenzo
> 
>> Signed-off-by: Yajun Deng <yajun.deng@...ux.dev>
>> ---
>> arch/arm64/kernel/pci.c | 7 +++++++
>> 1 file changed, 7 insertions(+)
>> 
>> diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c
>> index 2276689b5411..6ffd92126f65 100644
>> --- a/arch/arm64/kernel/pci.c
>> +++ b/arch/arm64/kernel/pci.c
>> @@ -29,6 +29,13 @@ int pcibios_alloc_irq(struct pci_dev *dev)
>> 
>> return 0;
>> }
>> +
>> +void pcibios_free_irq(struct pci_dev *dev)
>> +{
>> + if (!acpi_disabled)
>> + acpi_pci_irq_disable(dev);
>> +}
>> +
>> #endif
>> 
>> /*
>> --
>> 2.32.0