diff options
| author | Bjorn Helgaas <bhelgaas@google.com> | 2018-03-30 14:41:49 -0500 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2018-05-25 17:29:49 -0500 |
| commit | e5b1db0186bfb3bede41e412b27c9bcf2b336622 (patch) | |
| tree | a8108847dd2b5f06782536e6dd8fc2c9715d3a1b | |
| parent | 4695ca9d17a2f47e0be3011ef25a4d77b973b547 (diff) | |
| download | lwn-e5b1db0186bfb3bede41e412b27c9bcf2b336622.tar.gz lwn-e5b1db0186bfb3bede41e412b27c9bcf2b336622.zip | |
PCI: Remove unused pcie_get_minimum_link()
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>
| -rw-r--r-- | drivers/pci/pci.c | 43 | ||||
| -rw-r--r-- | include/linux/pci.h | 2 |
2 files changed, 0 insertions, 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 @@ -5070,49 +5070,6 @@ 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 * @dev: PCI device to query diff --git a/include/linux/pci.h b/include/linux/pci.h index 5eb97e198325..f7aa6d9f8999 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -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); |