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| author | Jesse Barnes <jbarnes@virtuousgeek.org> | 2010-10-20 00:07:57 +0400 |
|---|---|---|
| committer | Jesse Barnes <jbarnes@virtuousgeek.org> | 2011-05-12 02:18:40 +0400 |
| commit | b48d4425b602f5f4978299474743dbea130d940d (patch) | |
| tree | 7da23c264cab62bce753e60c4e8d5fbbb0aab0e7 /drivers/pci/pci.c | |
| parent | 69643e4829c5cd13bafe44a6b9f3eb2086e0f618 (diff) | |
| download | linux-b48d4425b602f5f4978299474743dbea130d940d.tar.xz | |
PCI: add ID-based ordering enable/disable support
Add support to allow drivers to enable/disable ID-based ordering. Where
supported, ID-based ordering can significantly improve the latency of
individual requests by preventing them from queueing up behind unrelated
traffic.
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Diffstat (limited to 'drivers/pci/pci.c')
| -rw-r--r-- | drivers/pci/pci.c | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 44d1c7c3876b..d0182bed7acc 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -1834,6 +1834,59 @@ void pci_enable_ari(struct pci_dev *dev) bridge->ari_enabled = 1; } +/** + * pci_enable_ido - enable ID-based ordering on a device + * @dev: the PCI device + * @type: which types of IDO to enable + * + * Enable ID-based ordering on @dev. @type can contain the bits + * %PCI_EXP_IDO_REQUEST and/or %PCI_EXP_IDO_COMPLETION to indicate + * which types of transactions are allowed to be re-ordered. + */ +void pci_enable_ido(struct pci_dev *dev, unsigned long type) +{ + int pos; + u16 ctrl; + + pos = pci_pcie_cap(dev); + if (!pos) + return; + + pci_read_config_word(dev, pos + PCI_EXP_DEVCTL2, &ctrl); + if (type & PCI_EXP_IDO_REQUEST) + ctrl |= PCI_EXP_IDO_REQ_EN; + if (type & PCI_EXP_IDO_COMPLETION) + ctrl |= PCI_EXP_IDO_CMP_EN; + pci_write_config_word(dev, pos + PCI_EXP_DEVCTL2, ctrl); +} +EXPORT_SYMBOL(pci_enable_ido); + +/** + * pci_disable_ido - disable ID-based ordering on a device + * @dev: the PCI device + * @type: which types of IDO to disable + */ +void pci_disable_ido(struct pci_dev *dev, unsigned long type) +{ + int pos; + u16 ctrl; + + if (!pci_is_pcie(dev)) + return; + + pos = pci_pcie_cap(dev); + if (!pos) + return; + + pci_read_config_word(dev, pos + PCI_EXP_DEVCTL2, &ctrl); + if (type & PCI_EXP_IDO_REQUEST) + ctrl &= ~PCI_EXP_IDO_REQ_EN; + if (type & PCI_EXP_IDO_COMPLETION) + ctrl &= ~PCI_EXP_IDO_CMP_EN; + pci_write_config_word(dev, pos + PCI_EXP_DEVCTL2, ctrl); +} +EXPORT_SYMBOL(pci_disable_ido); + static int pci_acs_enable; /** |