Re: [RFC KERNEL PATCH v3 3/3] PCI/sysfs: Add gsi sysfs for pci_dev

["Chen, Jiqian" <Jiqian.Chen@amd.com>]

On 2023/12/12 01:57, Roger Pau Monné wrote:
> On Mon, Dec 11, 2023 at 12:15:19AM +0800, Jiqian Chen wrote:
>> There is a need for some scenarios to use gsi sysfs.
>> For example, when xen passthrough a device to dumU, it will
>> use gsi to map pirq, but currently userspace can't get gsi
>> number.
>> So, add gsi sysfs for that and for other potential scenarios.
>>
>> Co-developed-by: Huang Rui <ray.huang@amd.com>
>> Signed-off-by: Jiqian Chen <Jiqian.Chen@amd.com>
>> ---
>>  drivers/acpi/pci_irq.c  |  1 +
>>  drivers/pci/pci-sysfs.c | 11 +++++++++++
>>  include/linux/pci.h     |  2 ++
>>  3 files changed, 14 insertions(+)
>>
>> diff --git a/drivers/acpi/pci_irq.c b/drivers/acpi/pci_irq.c
>> index 630fe0a34bc6..739a58755df2 100644
>> --- a/drivers/acpi/pci_irq.c
>> +++ b/drivers/acpi/pci_irq.c
>> @@ -449,6 +449,7 @@ int acpi_pci_irq_enable(struct pci_dev *dev)
>>  		kfree(entry);
>>  		return 0;
>>  	}
>> +	dev->gsi = gsi;
> 
> It would be better if the gsi if fetched without requiring calling
> acpi_pci_irq_enable(), as the gsi doesn't require the interrupt to be
> enabled.  The gsi is known at boot time and won't change for the
> lifetime of the device.
Do you have any suggest places to do this?

> 
>>  
>>  	rc = acpi_register_gsi(&dev->dev, gsi, triggering, polarity);
>>  	if (rc < 0) {
>> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
>> index 2321fdfefd7d..c51df88d079e 100644
>> --- a/drivers/pci/pci-sysfs.c
>> +++ b/drivers/pci/pci-sysfs.c
>> @@ -71,6 +71,16 @@ static ssize_t irq_show(struct device *dev,
>>  }
>>  static DEVICE_ATTR_RO(irq);
>>  
>> +static ssize_t gsi_show(struct device *dev,
>> +			struct device_attribute *attr,
>> +			char *buf)
>> +{
>> +	struct pci_dev *pdev = to_pci_dev(dev);
> 
> const
Do you mean "const struct pci_dev *pdev = to_pci_dev(dev);" ?

> 
> Thanks, Roger.

-- 
Best regards,
Jiqian Chen.