On Thu, May 03, 2018 at 03:00:43PM -0500, Bjorn Helgaas wrote:
> From: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
>
> In some cases pcie_get_minimum_link() returned misleading information
> because it found the slowest link and the narrowest link without
> considering the total bandwidth of the link.
>
> For example, consider a path with these two links:
>
> - 16.0 GT/s x1 link (16.0 * 10^9 * 128 / 130) * 1 / 8 = 1969 MB/s
> - 2.5 GT/s x16 link ( 2.5 * 10^9 * 8 / 10) * 16 / 8 = 4000 MB/s
>
> The available bandwidth of the path is limited by the 16 GT/s link to about
> 1969 MB/s, but pcie_get_minimum_link() returned 2.5 GT/s x1, which
> corresponds to only 250 MB/s.
>
> Callers should use pcie_print_link_status() instead, or
> pcie_bandwidth_available() if they need more detailed information.
>
> Remove pcie_get_minimum_link() since there are no callers left.
>
> Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Hi Jeff,
I got your note that you applied this to dev-queue. I assume that
means you also applied the preceding patches that removed all the
users. I got a note about ixgbe, but not the others, so I'm just
double-checking.
> ---
> drivers/pci/pci.c | 43 -------------------------------------------
> include/linux/pci.h | 2 --
> 2 files changed, 45 deletions(-)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index e597655a5643..4bafa817c40a 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -5069,49 +5069,6 @@ int pcie_set_mps(struct pci_dev *dev, int mps)
> }
> EXPORT_SYMBOL(pcie_set_mps);
>
> -/**
> - * pcie_get_minimum_link - determine minimum link settings of a PCI device
> - * @dev: PCI device to query
> - * @speed: storage for minimum speed
> - * @width: storage for minimum width
> - *
> - * This function will walk up the PCI device chain and determine the minimum
> - * link width and speed of the device.
> - */
> -int pcie_get_minimum_link(struct pci_dev *dev, enum pci_bus_speed *speed,
> - enum pcie_link_width *width)
> -{
> - int ret;
> -
> - *speed = PCI_SPEED_UNKNOWN;
> - *width = PCIE_LNK_WIDTH_UNKNOWN;
> -
> - while (dev) {
> - u16 lnksta;
> - enum pci_bus_speed next_speed;
> - enum pcie_link_width next_width;
> -
> - ret = pcie_capability_read_word(dev, PCI_EXP_LNKSTA, &lnksta);
> - if (ret)
> - return ret;
> -
> - next_speed = pcie_link_speed[lnksta & PCI_EXP_LNKSTA_CLS];
> - next_width = (lnksta & PCI_EXP_LNKSTA_NLW) >>
> - PCI_EXP_LNKSTA_NLW_SHIFT;
> -
> - if (next_speed < *speed)
> - *speed = next_speed;
> -
> - if (next_width < *width)
> - *width = next_width;
> -
> - dev = dev->bus->self;
> - }
> -
> - return 0;
> -}
> -EXPORT_SYMBOL(pcie_get_minimum_link);
> -
> /**
> * pcie_bandwidth_available - determine minimum link settings of a PCIe
> * device and its bandwidth limitation
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 73178a2fcee0..230615620a4a 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1079,8 +1079,6 @@ int pcie_get_readrq(struct pci_dev *dev);
> int pcie_set_readrq(struct pci_dev *dev, int rq);
> int pcie_get_mps(struct pci_dev *dev);
> int pcie_set_mps(struct pci_dev *dev, int mps);
> -int pcie_get_minimum_link(struct pci_dev *dev, enum pci_bus_speed *speed,
> - enum pcie_link_width *width);
> u32 pcie_bandwidth_available(struct pci_dev *dev, struct pci_dev **limiting_dev,
> enum pci_bus_speed *speed,
> enum pcie_link_width *width);
>
