From 586e584f666867af1767c7fce579cd0945c16165 Mon Sep 17 00:00:00 2001 From: Laurent Pinchart Date: Fri, 15 May 2015 02:00:09 +0300 Subject: [PATCH] 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. Signed-off-by: Laurent Pinchart --- drivers/iommu/of_iommu.c | 16 +++++++++++++--- drivers/of/device.c | 2 ++ 2 files changed, 15 insertions(+), 3 deletions(-) diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c index 136769a99822..37b7c3e4c0b6 100644 --- a/drivers/iommu/of_iommu.c +++ b/drivers/iommu/of_iommu.c @@ -172,8 +172,18 @@ struct iommu_ops *of_iommu_configure(struct device *dev, np = iommu_spec.np; ops = of_iommu_get_ops(np); - if (!ops || !ops->of_xlate || ops->of_xlate(dev, &iommu_spec)) + if (!ops) { + const struct of_device_id *oid; + + oid = of_match_node(&__iommu_of_table, np); + ops = oid ? ERR_PTR(-EPROBE_DEFER) : NULL; + goto err_put_node; + } + + if (!ops->of_xlate || ops->of_xlate(dev, &iommu_spec)) { + ops = NULL; goto err_put_node; + } of_node_put(np); idx++; @@ -183,7 +193,7 @@ struct iommu_ops *of_iommu_configure(struct device *dev, err_put_node: of_node_put(np); - return NULL; + return ops; } void __init of_iommu_init(void) @@ -194,7 +204,7 @@ void __init of_iommu_init(void) for_each_matching_node_and_match(np, matches, &match) { const of_iommu_init_fn init_fn = match->data; - if (init_fn(np)) + if (init_fn && init_fn(np)) pr_err("Failed to initialise IOMMU %s\n", of_node_full_name(np)); } diff --git a/drivers/of/device.c b/drivers/of/device.c index bc0078b56728..4996271a741c 100644 --- a/drivers/of/device.c +++ b/drivers/of/device.c @@ -149,6 +149,8 @@ int of_dma_configure_ops(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 "); -- 2.39.5