[+cc Robin]
On Thu, Mar 29, 2018 at 03:01:00AM -0700, Wang Dongsheng wrote:
> If SMMU probe failed, master should use swiotlb as dma ops.
> SMMU may probe failed with specified environment, so there
> are not any iommu resources in iommu_device_list.
>
> The master will always get EPROBE_DEFER from really_probe
> (dma_configure) but in fact SMMU has probe failed. The issue
> causes all of masters failed to be driven.
I added Robin to pick his brain. An alternative would consist
in using a bus notifier to prevent deferred probing once the SMMU
driver probing failed but that seems backwards given that a major
reason to move to deferred probing was to remove the bus notifiers
dependency in the first place.
It seems to me this is both an OF/ACPI issue - it is not an IORT
only problem.
Lorenzo
> Signed-off-by: Wang Dongsheng <dongsheng.wang@xxxxxxxxxxxxxxxx>
> ---
> drivers/acpi/arm64/iort.c | 39 +++++++++++++++++++++++++++++++++------
> 1 file changed, 33 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> index e2f7bdd..a6f4c27 100644
> --- a/drivers/acpi/arm64/iort.c
> +++ b/drivers/acpi/arm64/iort.c
> @@ -774,17 +774,45 @@ static int arm_smmu_iort_xlate(struct device *dev, u32 streamid,
> return ret;
> }
>
> -static inline bool iort_iommu_driver_enabled(u8 type)
> +static int iort_check_dev_dl_status(struct device *dev, void *data)
> {
> + struct fwnode_handle *fwnode = data;
> +
> + if (dev->fwnode != fwnode)
> + return 0;
> +
> + if (dev->links.status == DL_DEV_PROBE_FAILED)
> + return -ENODEV;
> +
> + return -EPROBE_DEFER;
> +}
> +
> +static int iort_iommu_driver_enabled(u8 type, struct fwnode_handle *fwnode)
> +{
> + bool buildin;
> + int ret;
> +
> switch (type) {
> case ACPI_IORT_NODE_SMMU_V3:
> - return IS_BUILTIN(CONFIG_ARM_SMMU_V3);
> + buildin = IS_BUILTIN(CONFIG_ARM_SMMU_V3);
> + break;
> case ACPI_IORT_NODE_SMMU:
> - return IS_BUILTIN(CONFIG_ARM_SMMU);
> + buildin = IS_BUILTIN(CONFIG_ARM_SMMU);
> + break;
> default:
> pr_warn("IORT node type %u does not describe an SMMU\n", type);
> - return false;
> + buildin = false;
> }
> +
> + if (!buildin)
> + return -ENODEV;
> +
> + ret = bus_for_each_dev(&platform_bus_type, NULL, fwnode,
> + iort_check_dev_dl_status);
> + if (!ret)
> + return -EPROBE_DEFER;
> +
> + return ret;
> }
>
> #ifdef CONFIG_IOMMU_API
> @@ -919,8 +947,7 @@ static int iort_iommu_xlate(struct device *dev, struct acpi_iort_node *node,
> */
> ops = iommu_ops_from_fwnode(iort_fwnode);
> if (!ops)
> - return iort_iommu_driver_enabled(node->type) ?
> - -EPROBE_DEFER : -ENODEV;
> + return iort_iommu_driver_enabled(node->type, iort_fwnode);
>
> return arm_smmu_iort_xlate(dev, streamid, iort_fwnode, ops);
> }
> --
> 2.7.4
>
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