Commit da27f4b3 authored by Bjorn Helgaas's avatar Bjorn Helgaas

PCI: Add comment about needing pci_msi_off() even when CONFIG_PCI_MSI=n

Per f5f2b131 ("msi: sanely support hardware level msi disabling"), we
want pci_msi_off() to work even if MSI support is not compiled into the
kernel, and there are existing callers that use it when CONFIG_PCI_MSI=n.
This adds a comment to that effect.

No functional change.
Signed-off-by: default avatarBjorn Helgaas <>
parent 699c1985
......@@ -3059,18 +3059,23 @@ bool pci_check_and_unmask_intx(struct pci_dev *dev)
* pci_msi_off - disables any msi or msix capabilities
* pci_msi_off - disables any MSI or MSI-X capabilities
* @dev: the PCI device to operate on
* If you want to use msi see pci_enable_msi and friends.
* This is a lower level primitive that allows us to disable
* msi operation at the device level.
* If you want to use MSI, see pci_enable_msi() and friends.
* This is a lower-level primitive that allows us to disable
* MSI operation at the device level.
void pci_msi_off(struct pci_dev *dev)
int pos;
u16 control;
* This looks like it could go in msi.c, but we need it even when
* CONFIG_PCI_MSI=n. For the same reason, we can't use
* dev->msi_cap or dev->msix_cap here.
pos = pci_find_capability(dev, PCI_CAP_ID_MSI);
if (pos) {
pci_read_config_word(dev, pos + PCI_MSI_FLAGS, &control);
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