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

[Dave Jiang <dave.jiang@xxxxxxxxx>]

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@xxxxxxxxx>
> > ---
> >   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 {