diff options
author | Marc Zyngier <marc.zyngier@arm.com> | 2018-05-31 16:21:43 +0100 |
---|---|---|
committer | Marc Zyngier <marc.zyngier@arm.com> | 2018-07-27 10:01:24 +0100 |
commit | 30800b3a1fb14c6f143db5616a4aaea9fef94af3 (patch) | |
tree | 48bcc72a292e8e87a2b7465ac7e6b35a8800c875 | |
parent | 12b2905af183c931bedcab4292c81d3a415e080f (diff) | |
download | linux-30800b3a1fb14c6f143db5616a4aaea9fef94af3.tar.bz2 |
irqchip/gic-v3-its: Reduce minimum LPI allocation to 1 for PCI devices
Allocating a minimum of 32 LPIs per PCI device, let's reduce it to
be just 1, as most devices do not need that many interrupts.
We still have to special-case DevID 0, as there is plenty of broken
HW around where the PCI RID is not presented as a DevID to the ITS,
and all the devices are presented as DevID 0. In this case, we keep
the 32 minimal allocation.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
-rw-r--r-- | drivers/irqchip/irq-gic-v3-its-pci-msi.c | 14 |
1 files changed, 11 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 75c3cafabc6a..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; @@ -86,9 +86,17 @@ 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); - /* Allocate at least 32 MSIs, and always as a power of 2 */ + /* + * 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); - nvec = max_t(int, 32, roundup_pow_of_two(nvec)); + 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); } |