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SubjectRe: [PATCH v2 23/33] iommu/mediatek-v1 Convert to probe/release_device() call-backs
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On Tue, 2020-04-14 at 15:15 +0200, Joerg Roedel wrote:
> From: Joerg Roedel <jroedel@suse.de>
>
> Convert the Mediatek-v1 IOMMU driver to use the probe_device() and
> release_device() call-backs of iommu_ops, so that the iommu core code
> does the group and sysfs setup.
>
> Signed-off-by: Joerg Roedel <jroedel@suse.de>
> ---
> drivers/iommu/mtk_iommu_v1.c | 50 +++++++++++++++---------------------
> 1 file changed, 20 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/iommu/mtk_iommu_v1.c b/drivers/iommu/mtk_iommu_v1.c
> index a31be05601c9..7bdd74c7cb9f 100644
> --- a/drivers/iommu/mtk_iommu_v1.c
> +++ b/drivers/iommu/mtk_iommu_v1.c
> @@ -416,14 +416,12 @@ static int mtk_iommu_create_mapping(struct device *dev,
> return 0;
> }
>
> -static int mtk_iommu_add_device(struct device *dev)
> +static struct iommu_device *mtk_iommu_probe_device(struct device *dev)
> {
> struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
> - struct dma_iommu_mapping *mtk_mapping;
> struct of_phandle_args iommu_spec;
> struct of_phandle_iterator it;
> struct mtk_iommu_data *data;
> - struct iommu_group *group;
> int err;
>
> of_for_each_phandle(&it, err, dev->of_node, "iommus",
> @@ -442,35 +440,28 @@ static int mtk_iommu_add_device(struct device *dev)
> }
>
> if (!fwspec || fwspec->ops != &mtk_iommu_ops)
> - return -ENODEV; /* Not a iommu client device */
> + return ERR_PTR(-ENODEV); /* Not a iommu client device */
>
> - /*
> - * This is a short-term bodge because the ARM DMA code doesn't
> - * understand multi-device groups, but we have to call into it
> - * successfully (and not just rely on a normal IOMMU API attach
> - * here) in order to set the correct DMA API ops on @dev.
> - */
> - group = iommu_group_alloc();
> - if (IS_ERR(group))
> - return PTR_ERR(group);
> + data = dev_iommu_priv_get(dev);
>
> - err = iommu_group_add_device(group, dev);
> - iommu_group_put(group);
> - if (err)
> - return err;
> + return &data->iommu;
> +}
>
> - data = dev_iommu_priv_get(dev);
> +static void mtk_iommu_probe_finalize(struct device *dev)
> +{
> + struct dma_iommu_mapping *mtk_mapping;
> + struct mtk_iommu_data *data;
> + int err;
> +
> + data = dev_iommu_priv_get(dev);
> mtk_mapping = data->dev->archdata.iommu;
> - err = arm_iommu_attach_device(dev, mtk_mapping);
> - if (err) {
> - iommu_group_remove_device(dev);
> - return err;
> - }
>
> - return iommu_device_link(&data->iommu, dev);
> + err = arm_iommu_attach_device(dev, mtk_mapping);
> + if (err)
> + dev_err(dev, "Can't create IOMMU mapping - DMA-OPS will not work\n");


Hi Joerg,

Thanks very much for this patch.

This arm_iommu_attach_device is called just as we expected.

But it will fail in this callstack as the group->mutex was tried to
be re-locked...

[<c0938e8c>] (iommu_attach_device) from [<c0317590>]
(__arm_iommu_attach_device+0x34/0x90)
[<c0317590>] (__arm_iommu_attach_device) from [<c03175f8>]
(arm_iommu_attach_device+0xc/0x20)
[<c03175f8>] (arm_iommu_attach_device) from [<c09432cc>]
(mtk_iommu_probe_finalize+0x34/0x50)
[<c09432cc>] (mtk_iommu_probe_finalize) from [<c093a8ac>]
(bus_iommu_probe+0x2a8/0x2c4)
[<c093a8ac>] (bus_iommu_probe) from [<c093a950>] (bus_set_iommu
+0x88/0xd4)
[<c093a950>] (bus_set_iommu) from [<c0943c74>] (mtk_iommu_probe
+0x2f8/0x364)


> }
>
> -static void mtk_iommu_remove_device(struct device *dev)
> +static void mtk_iommu_release_device(struct device *dev)
> {
> struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
> struct mtk_iommu_data *data;
> @@ -479,9 +470,6 @@ static void mtk_iommu_remove_device(struct device *dev)
> return;
>
> data = dev_iommu_priv_get(dev);
> - iommu_device_unlink(&data->iommu, dev);
> -
> - iommu_group_remove_device(dev);
> iommu_fwspec_free(dev);
> }
>
> @@ -534,8 +522,10 @@ static const struct iommu_ops mtk_iommu_ops = {
> .map = mtk_iommu_map,
> .unmap = mtk_iommu_unmap,
> .iova_to_phys = mtk_iommu_iova_to_phys,
> - .add_device = mtk_iommu_add_device,
> - .remove_device = mtk_iommu_remove_device,
> + .probe_device = mtk_iommu_probe_device,
> + .probe_finalize = mtk_iommu_probe_finalize,
> + .release_device = mtk_iommu_release_device,
> + .device_group = generic_device_group,
> .pgsize_bitmap = ~0UL << MT2701_IOMMU_PAGE_SHIFT,
> };
>

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