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iommu: of: Handle IOMMU lookup failure with deferred probing or error

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Failures to look up an IOMMU when parsing the DT iommus property need to
be handled separately from the .of_xlate() failures to support deferred
probing.

The lack of a registered IOMMU can be caused by the lack of a driver for
the IOMMU, the IOMMU device probe not having been performed yet, having
been deferred, or having failed.

The first case occurs when the device tree describes the bus master and
IOMMU topology correctly but no device driver exists for the IOMMU yet
or the device driver has not been compiled in. Return NULL, the caller
will configure the device without an IOMMU.

The second and third cases are handled by deferring the probe of the bus
master device which will eventually get reprobed after the IOMMU.

The last case is currently handled by deferring the probe of the bus
master device as well. A mechanism to either configure the bus master
device without an IOMMU or to fail the bus master device probe depending
on whether the IOMMU is optional or mandatory would be a good
enhancement.

Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Laurent Pichart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Sricharan R <sricharan@codeaurora.org>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Laurent Pinchart
2017-04-10 16:51:02 +05:30
committed by Joerg Roedel
parent 09515ef5dd
commit 7b07cbefb6
4 changed files with 18 additions and 9 deletions
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5
drivers/base/dma-mapping.c
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@@ -353,6 +353,7 @@ int dma_configure(struct device *dev)
{
struct device *bridge = NULL, *dma_dev = dev;
enum dev_dma_attr attr;
int ret = 0;
if (dev_is_pci(dev)) {
bridge = pci_get_host_bridge_device(to_pci_dev(dev));
@@ -363,7 +364,7 @@ int dma_configure(struct device *dev)
}
if (dma_dev->of_node) {
of_dma_configure(dev, dma_dev->of_node);
ret = of_dma_configure(dev, dma_dev->of_node);
} else if (has_acpi_companion(dma_dev)) {
attr = acpi_get_dma_attr(to_acpi_device_node(dma_dev->fwnode));
if (attr != DEV_DMA_NOT_SUPPORTED)
@@ -373,7 +374,7 @@ int dma_configure(struct device *dev)
if (bridge)
pci_put_host_bridge_device(bridge);
return 0;
return ret;
}
void dma_deconfigure(struct device *dev)