From 7b07cbefb68d486febf47e13b570fed53d9296b4 Mon Sep 17 00:00:00 2001 From: Laurent Pinchart Date: Mon, 10 Apr 2017 16:51:02 +0530 Subject: iommu: of: Handle IOMMU lookup failure with deferred probing or error 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 Reviewed-by: Robin Murphy Acked-by: Rob Herring Signed-off-by: Laurent Pichart Signed-off-by: Sricharan R Signed-off-by: Joerg Roedel --- drivers/of/device.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) (limited to 'drivers/of') diff --git a/drivers/of/device.c b/drivers/of/device.c index e1ae9e7104a1..8bd3d8c09435 100644 --- a/drivers/of/device.c +++ b/drivers/of/device.c @@ -82,7 +82,7 @@ int of_device_add(struct platform_device *ofdev) * can use a platform bus notifier and handle BUS_NOTIFY_ADD_DEVICE events * to fix up DMA configuration. */ -void of_dma_configure(struct device *dev, struct device_node *np) +int of_dma_configure(struct device *dev, struct device_node *np) { u64 dma_addr, paddr, size; int ret; @@ -123,7 +123,7 @@ void of_dma_configure(struct device *dev, struct device_node *np) if (!size) { dev_err(dev, "Adjusted size 0x%llx invalid\n", size); - return; + return -EINVAL; } dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", offset); } @@ -144,10 +144,15 @@ void of_dma_configure(struct device *dev, struct device_node *np) coherent ? " " : " not "); iommu = of_iommu_configure(dev, np); + if (IS_ERR(iommu)) + return PTR_ERR(iommu); + dev_dbg(dev, "device is%sbehind an iommu\n", iommu ? " " : " not "); arch_setup_dma_ops(dev, dma_addr, size, iommu, coherent); + + return 0; } EXPORT_SYMBOL_GPL(of_dma_configure); -- cgit