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authorMichael Ellerman <michael@ellerman.id.au>2009-02-11 22:27:02 +1100
committerJesse Barnes <jbarnes@hobbes.lan>2009-03-19 19:29:34 -0700
commitb5fbf53324f65646154e172af350674d5a2a1629 (patch)
tree6310f1629c3112e240b151862b7f0b357045649e /drivers/pci
parent35e1801ea637810830e653ffe7ff62c7048ae03a (diff)
PCI/MSI: Allow arch code to return the number of MSI-X available
There is code in msix_capability_init() which, when the requested number of MSI-X couldn't be allocated, calculates how many MSI-X /could/ be allocated and returns that to the driver. That allows the driver to then make a second request, with a number of MSIs that should succeed. The current code requires the arch code to setup as many msi_descs as it can, and then return to the generic code. On some platforms the arch code may already know how many MSI-X it can allocate, before it sets up any of the msi_descs. So change the logic such that if the arch code returns a positive error code, that is taken to be the number of MSI-X that could be allocated. If the error code is negative we still calculate the number available using the old method. Because it's a little subtle, make sure the error return code from arch_setup_msi_irq() is always negative. That way only implementations of arch_setup_msi_irqs() need to be careful about returning a positive error code. Signed-off-by: Michael Ellerman <michael@ellerman.id.au> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Diffstat (limited to 'drivers/pci')
-rw-r--r--drivers/pci/msi.c21
1 files changed, 12 insertions, 9 deletions
diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 33adf323f06..dceea56f734 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -42,8 +42,10 @@ int arch_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
list_for_each_entry(entry, &dev->msi_list, list) {
ret = arch_setup_msi_irq(dev, entry);
- if (ret)
+ if (ret < 0)
return ret;
+ if (ret > 0)
+ return -ENOSPC;
}
return 0;
@@ -487,7 +489,9 @@ static int msix_capability_init(struct pci_dev *dev,
}
ret = arch_setup_msi_irqs(dev, nvec, PCI_CAP_ID_MSIX);
- if (ret) {
+ if (ret < 0) {
+ /* If we had some success report the number of irqs
+ * we succeeded in setting up. */
int avail = 0;
list_for_each_entry(entry, &dev->msi_list, list) {
if (entry->irq != 0) {
@@ -495,14 +499,13 @@ static int msix_capability_init(struct pci_dev *dev,
}
}
- msi_free_irqs(dev);
+ if (avail != 0)
+ ret = avail;
+ }
- /* If we had some success report the number of irqs
- * we succeeded in setting up.
- */
- if (avail == 0)
- avail = ret;
- return avail;
+ if (ret) {
+ msi_free_irqs(dev);
+ return ret;
}
i = 0;