ACPI / scan: Refactor _CCA enforcement

Rather than checking the DMA attribute at each callsite, just pass it
through for acpi_dma_configure() to handle directly. That can then deal
with the relatively exceptional DEV_DMA_NOT_SUPPORTED case by explicitly
installing dummy DMA ops instead of just skipping setup entirely. This
will then free up the dev->dma_ops == NULL case for some valuable
fastpath optimisations.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Tested-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Tony Luck <tony.luck@intel.com>

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index bd1c59f..b75ae34 100644 (file)
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -1456,6 +1456,11 @@ int acpi_dma_configure(struct device *dev, enum dev_dma_attr attr)
        const struct iommu_ops *iommu;
        u64 dma_addr = 0, size = 0;
 
+       if (attr == DEV_DMA_NOT_SUPPORTED) {
+               set_dma_ops(dev, &dma_dummy_ops);
+               return 0;
+       }
+
        iort_dma_setup(dev, &dma_addr, &size);
 
        iommu = iort_iommu_configure(dev);

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index eae8419..c1ddf19 100644 (file)
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -1138,8 +1138,7 @@ int platform_dma_configure(struct device *dev)
                ret = of_dma_configure(dev, dev->of_node, true);
        } else if (has_acpi_companion(dev)) {
                attr = acpi_get_dma_attr(to_acpi_device_node(dev->fwnode));
-               if (attr != DEV_DMA_NOT_SUPPORTED)
-                       ret = acpi_dma_configure(dev, attr);
+               ret = acpi_dma_configure(dev, attr);
        }
 
        return ret;

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index bef17c3..1b58e05 100644 (file)
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -1602,8 +1602,7 @@ static int pci_dma_configure(struct device *dev)
                struct acpi_device *adev = to_acpi_device_node(bridge->fwnode);
                enum dev_dma_attr attr = acpi_get_dma_attr(adev);
 
-               if (attr != DEV_DMA_NOT_SUPPORTED)
-                       ret = acpi_dma_configure(dev, attr);
+               ret = acpi_dma_configure(dev, acpi_get_dma_attr(adev));
        }
 
        pci_put_host_bridge_device(bridge);