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PCI: Remove unused pcie_get_minimum_link()

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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@google.com>
This commit is contained in:
Bjorn Helgaas 2018-03-30 14:41:49 -05:00
parent 4695ca9d17
commit e5b1db0186
2 changed files with 0 additions and 45 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

43
drivers/pci/pci.c
View File

@ -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

2
include/linux/pci.h
View File

@ -1080,8 +1080,6 @@ 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);