Re: [PATCH 11/18] PCI: Export pcie_get_width() using the code from sysfs PCI link width show function

[Dave Jiang <dave.jiang@intel.com>]

On 2/6/23 3:43 PM, Bjorn Helgaas wrote:
> On Mon, Feb 06, 2023 at 01:51:01PM -0700, Dave Jiang wrote:
>> Move the logic in current_link_width_show() to a common function and export
>> that functiuon as pcie_get_width() to allow other drivers to to retrieve
>> the current negotiated link width.
> 
> s/a common function and export that functiuon and export that functiuon as//
> 
> I don't see the module caller of this, so not clear on why it needs to
> be exported.

You are right. I think I was using it before I found 
pcie_bandwidth_available() call. I will drop.

> 
>> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
>> ---
>>   drivers/pci/pci-sysfs.c |    9 +--------
>>   drivers/pci/pci.c       |   20 ++++++++++++++++++++
>>   include/linux/pci.h     |    1 +
>>   3 files changed, 22 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
>> index 0217bb5ca8fa..139096c39380 100644
>> --- a/drivers/pci/pci-sysfs.c
>> +++ b/drivers/pci/pci-sysfs.c
>> @@ -215,15 +215,8 @@ static ssize_t current_link_width_show(struct device *dev,
>>   				       struct device_attribute *attr, char *buf)
>>   {
>>   	struct pci_dev *pci_dev = to_pci_dev(dev);
>> -	u16 linkstat;
>> -	int err;
>>   
>> -	err = pcie_capability_read_word(pci_dev, PCI_EXP_LNKSTA, &linkstat);
>> -	if (err)
>> -		return -EINVAL;
>> -
>> -	return sysfs_emit(buf, "%u\n",
>> -		(linkstat & PCI_EXP_LNKSTA_NLW) >> PCI_EXP_LNKSTA_NLW_SHIFT);
>> +	return sysfs_emit(buf, "%u\n", pcie_get_width(pci_dev));
>>   }
>>   static DEVICE_ATTR_RO(current_link_width);
>>   
>> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
>> index d0131b5623b1..0858fa2f1c2d 100644
>> --- a/drivers/pci/pci.c
>> +++ b/drivers/pci/pci.c
>> @@ -6235,6 +6235,26 @@ enum pci_bus_speed pcie_get_speed(struct pci_dev *dev)
>>   }
>>   EXPORT_SYMBOL(pcie_get_speed);
>>   
>> +/**
>> + * pcie_get_width - query for the PCI device's current link width
>> + * @dev: PCI device to query
>> + *
>> + * Query the PCI device current negoiated width.
>> + */
>> +
>> +enum pcie_link_width pcie_get_width(struct pci_dev *dev)
>> +{
>> +	u16 linkstat;
>> +	int err;
>> +
>> +	err = pcie_capability_read_word(dev, PCI_EXP_LNKSTA, &linkstat);
>> +	if (err)
>> +		return PCIE_LNK_WIDTH_UNKNOWN;
>> +
>> +	return FIELD_GET(PCI_EXP_LNKSTA_NLW, linkstat);
>> +}
>> +EXPORT_SYMBOL(pcie_get_width);
>> +
>>   /**
>>    * pcie_bandwidth_capable - calculate a PCI device's link bandwidth capability
>>    * @dev: PCI device
>> diff --git a/include/linux/pci.h b/include/linux/pci.h
>> index 6a065986ff8f..21eca09a98e2 100644
>> --- a/include/linux/pci.h
>> +++ b/include/linux/pci.h
>> @@ -305,6 +305,7 @@ enum pci_bus_speed {
>>   
>>   enum pci_bus_speed pcie_get_speed(struct pci_dev *dev);
>>   enum pci_bus_speed pcie_get_speed_cap(struct pci_dev *dev);
>> +enum pcie_link_width pcie_get_width(struct pci_dev *dev);
>>   enum pcie_link_width pcie_get_width_cap(struct pci_dev *dev);
>>   
>>   struct pci_vpd {
>>
>>