iommu/arm-smmu-v3: limit reporting of MSI allocation failures

Currently, the arm-smmu-v3 driver expects to allocate MSIs for all SMMUs
with FEAT_MSI set. This results in unwarranted "failed to allocate MSIs"
warnings being printed on systems where FW was either deliberately
configured to force the use of SMMU wired interrupts -or- is altogether
incapable of describing SMMU MSI topology (ACPI IORT prior to rev.C).

Remedy this by checking msi_domain before attempting to allocate SMMU
MSIs.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Nate Watterson <nwatters@codeaurora.org>
Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index ebf22e9..d9b944e 100644 (file)
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -2328,10 +2328,15 @@ static void arm_smmu_setup_msis(struct arm_smmu_device *smmu)
        if (!(smmu->features & ARM_SMMU_FEAT_MSI))
                return;
 
+       if (!dev->msi_domain) {
+               dev_info(smmu->dev, "msi_domain absent - falling back to wired irqs\n");
+               return;
+       }
+
        /* Allocate MSIs for evtq, gerror and priq. Ignore cmdq */
        ret = platform_msi_domain_alloc_irqs(dev, nvec, arm_smmu_write_msi_msg);
        if (ret) {
-               dev_warn(dev, "failed to allocate MSIs\n");
+               dev_warn(dev, "failed to allocate MSIs - falling back to wired irqs\n");
                return;
        }