[PATCH v7 02/12] iommu/mediatek-v1: Free the existed fwspec if the master dev already has

Yong Wu
2021-07-30T02:53:53Z

When the iommu master device enters of_iommu_xlate, the ops may be
NULL(iommu dev is defered), then it will initialize the fwspec here:

[<c0c9c5bc>] (dev_iommu_fwspec_set) from [<c06bda80>]
(iommu_fwspec_init+0xbc/0xd4)
[<c06bd9c4>] (iommu_fwspec_init) from [<c06c0db4>]
(of_iommu_xlate+0x7c/0x12c)
[<c06c0d38>] (of_iommu_xlate) from [<c06c10e8>]
(of_iommu_configure+0x144/0x1e8)

BUT the mtk_iommu_v1.c only supports arm32, the probing flow still is a bit
weird. We always expect create the fwspec internally. otherwise it will
enter here and return fail.

static int mtk_iommu_create_mapping(struct device *dev,
struct of_phandle_args *args)
{
...
if (!fwspec) {
....
} else if (dev_iommu_fwspec_get(dev)->ops != &mtk_iommu_ops) {
>>>>>>>>>>Enter here. return fail.<<<<<<<<<<<<
return -EINVAL;
}
...
}

Thus, Free the existed fwspec if the master device already has fwspec.

This issue is reported at:
https://lore.kernel.org/linux-mediatek/trinity-7d9ebdc9-4849-4d93-bfb5-429dcb4ee449-1626253158870@3c-app-gmx-bs01/

Reported-by: Frank Wunderlich <frank-w@public-files.de>
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
---
No need fix tag, since it is ok before this cleanup patchset.
the issue may be revealed by the patch adding probe_defer what adjust the
device probing sequency.
---
drivers/iommu/mtk_iommu_v1.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/drivers/iommu/mtk_iommu_v1.c b/drivers/iommu/mtk_iommu_v1.c
index 778e66f5f1aa..6861eeab182d 100644
--- a/drivers/iommu/mtk_iommu_v1.c
+++ b/drivers/iommu/mtk_iommu_v1.c
@@ -426,6 +426,15 @@ static struct iommu_device *mtk_iommu_probe_device(struct device *dev)
struct mtk_iommu_data *data;
int err, idx = 0;

+ /*
+ * In the deferred case, free the existed fwspec if the dev already has,
+ * Always initialize the fwspec internally.
+ */
+ if (fwspec) {
+ iommu_fwspec_free(dev);
+ fwspec = dev_iommu_fwspec_get(dev);
+ }
+
while (!of_parse_phandle_with_args(dev->of_node, "iommus",
"#iommu-cells",
idx, &iommu_spec)) {
--
2.18.0