On 04/04/17 11:18, Sricharan R wrote:
> From: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
>
> 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.
Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx>
> Tested-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> Signed-off-by: Laurent Pichart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
> Signed-off-by: Sricharan R <sricharan@xxxxxxxxxxxxxx>
> ---
> drivers/base/dma-mapping.c | 5 +++--
> drivers/iommu/of_iommu.c | 4 ++--
> drivers/of/device.c | 7 ++++++-
> include/linux/of_device.h | 9 ++++++---
> 4 files changed, 17 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c
> index 449b948..82bd45c 100644
> --- a/drivers/base/dma-mapping.c
> +++ b/drivers/base/dma-mapping.c
> @@ -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)
> diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
> index c8be889..9f44ee8 100644
> --- a/drivers/iommu/of_iommu.c
> +++ b/drivers/iommu/of_iommu.c
> @@ -236,7 +236,7 @@ const struct iommu_ops *of_iommu_configure(struct device *dev,
> ops = ERR_PTR(err);
> }
>
> - return IS_ERR(ops) ? NULL : ops;
> + return ops;
> }
>
> static int __init of_iommu_init(void)
> @@ -247,7 +247,7 @@ static int __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 c2ae6bb..bea8aec 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;
> @@ -129,10 +129,15 @@ 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);
>
> diff --git a/include/linux/of_device.h b/include/linux/of_device.h
> index af98455..2cacdd8 100644
> --- a/include/linux/of_device.h
> +++ b/include/linux/of_device.h
> @@ -55,7 +55,7 @@ static inline struct device_node *of_cpu_device_node_get(int cpu)
> return of_node_get(cpu_dev->of_node);
> }
>
> -void of_dma_configure(struct device *dev, struct device_node *np);
> +int of_dma_configure(struct device *dev, struct device_node *np);
> void of_dma_deconfigure(struct device *dev);
> #else /* CONFIG_OF */
>
> @@ -104,8 +104,11 @@ static inline struct device_node *of_cpu_device_node_get(int cpu)
> {
> return NULL;
> }
> -static inline void of_dma_configure(struct device *dev, struct device_node *np)
> -{}
> +
> +static inline int of_dma_configure(struct device *dev, struct device_node *np)
> +{
> + return 0;
> +}
> static inline void of_dma_deconfigure(struct device *dev)
> {}
> #endif /* CONFIG_OF */
>
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