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path: root/drivers/irqchip/irq-gic-v3-its-pci-msi.c
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Diffstat (limited to 'drivers/irqchip/irq-gic-v3-its-pci-msi.c')
-rw-r--r--drivers/irqchip/irq-gic-v3-its-pci-msi.c16
1 files changed, 13 insertions, 3 deletions
diff --git a/drivers/irqchip/irq-gic-v3-its-pci-msi.c b/drivers/irqchip/irq-gic-v3-its-pci-msi.c
index 25a98de5cfb2..8d6d009d1d58 100644
--- a/drivers/irqchip/irq-gic-v3-its-pci-msi.c
+++ b/drivers/irqchip/irq-gic-v3-its-pci-msi.c
@@ -66,7 +66,7 @@ static int its_pci_msi_prepare(struct irq_domain *domain, struct device *dev,
{
struct pci_dev *pdev, *alias_dev;
struct msi_domain_info *msi_info;
- int alias_count = 0;
+ int alias_count = 0, minnvec = 1;
if (!dev_is_pci(dev))
return -EINVAL;
@@ -86,8 +86,18 @@ static int its_pci_msi_prepare(struct irq_domain *domain, struct device *dev,
/* ITS specific DeviceID, as the core ITS ignores dev. */
info->scratchpad[0].ul = pci_msi_domain_get_msi_rid(domain, pdev);
- return msi_info->ops->msi_prepare(domain->parent,
- dev, max(nvec, alias_count), info);
+ /*
+ * Always allocate a power of 2, and special case device 0 for
+ * broken systems where the DevID is not wired (and all devices
+ * appear as DevID 0). For that reason, we generously allocate a
+ * minimum of 32 MSIs for DevID 0. If you want more because all
+ * your devices are aliasing to DevID 0, consider fixing your HW.
+ */
+ nvec = max(nvec, alias_count);
+ if (!info->scratchpad[0].ul)
+ minnvec = 32;
+ nvec = max_t(int, minnvec, roundup_pow_of_two(nvec));
+ return msi_info->ops->msi_prepare(domain->parent, dev, nvec, info);
}
static struct msi_domain_ops its_pci_msi_ops = {