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SubjectRe: [PATCH v1 6/9] iommu/tegra: gart: Ignore devices without IOMMU phandle in DT
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Hi Dmitry,

On 08/05/18 19:16, Dmitry Osipenko wrote:
> GART can't handle all devices, ignore devices that aren't related to GART.
> Device tree must explicitly assign GART IOMMU to the devices.
>
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
> drivers/iommu/tegra-gart.c | 33 ++++++++++++++++++++++++++++++++-
> 1 file changed, 32 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/tegra-gart.c b/drivers/iommu/tegra-gart.c
> index 39305224c48d..5b2d27620350 100644
> --- a/drivers/iommu/tegra-gart.c
> +++ b/drivers/iommu/tegra-gart.c
> @@ -366,6 +366,26 @@ static void gart_iommu_remove_device(struct device *dev)
> iommu_device_unlink(&gart_handle->iommu, dev);
> }
>
> +static int gart_iommu_check_device(struct gart_device *gart,
> + struct device *dev);
> +
> +struct iommu_group *gart_iommu_device_group(struct device *dev)
> +{
> + int err;
> +
> + err = gart_iommu_check_device(gart_handle, dev);
> + if (err)
> + return ERR_PTR(err);
> +
> + return generic_device_group(dev);
> +}
> +
> +static int gart_iommu_of_xlate(struct device *dev,
> + struct of_phandle_args *args)
> +{
> + return 0;
> +}
> +
> static const struct iommu_ops gart_iommu_ops = {
> .capable = gart_iommu_capable,
> .domain_alloc = gart_iommu_domain_alloc,
> @@ -374,14 +394,24 @@ static const struct iommu_ops gart_iommu_ops = {
> .detach_dev = gart_iommu_detach_dev,
> .add_device = gart_iommu_add_device,
> .remove_device = gart_iommu_remove_device,
> - .device_group = generic_device_group,
> + .device_group = gart_iommu_device_group,
> .map = gart_iommu_map,
> .map_sg = default_iommu_map_sg,
> .unmap = gart_iommu_unmap,
> .iova_to_phys = gart_iommu_iova_to_phys,
> .pgsize_bitmap = GART_IOMMU_PGSIZES,
> + .of_xlate = gart_iommu_of_xlate,
> };
>
> +static int gart_iommu_check_device(struct gart_device *gart,
> + struct device *dev)
> +{
> + if (!dev->iommu_fwspec || dev->iommu_fwspec->ops != &gart_iommu_ops)
> + return -ENODEV;

Conceptually, it would be better to verify this in .add_device *before*
calling iommu_group_get_for_dev(). That would also align with what other
drivers do, and let you save introducing the .device_group callback
until the real implementation in the later patch.

Robin.

> +
> + return 0;
> +}
> +
> static int tegra_gart_suspend(struct device *dev)
> {
> struct gart_device *gart = dev_get_drvdata(dev);
> @@ -462,6 +492,7 @@ static int tegra_gart_probe(struct platform_device *pdev)
> }
>
> iommu_device_set_ops(&gart->iommu, &gart_iommu_ops);
> + iommu_device_set_fwnode(&gart->iommu, dev->fwnode);
>
> ret = iommu_device_register(&gart->iommu);
> if (ret) {
>

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