[PATCH 5.15 734/913] media: iommu/mediatek-v1: Free the existed fwspec if the master dev already has

From: Greg Kroah-Hartman
Date: Tue Apr 05 2022 - 18:41:07 EST

From: Yong Wu <yong.wu@xxxxxxxxxxxx>

[ Upstream commit 822a2ed8c606caf6a11b1a180b8e46292bd77d71 ]

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>]
[<c06bd9c4>] (iommu_fwspec_init) from [<c06c0db4>]
[<c06c0d38>] (of_iommu_xlate) from [<c06c10e8>]

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:

Reported-by: Frank Wunderlich <frank-w@xxxxxxxxxxxxxxx>
Tested-by: Frank Wunderlich <frank-w@xxxxxxxxxxxxxxx> # BPI-R2/MT7623
Signed-off-by: Yong Wu <yong.wu@xxxxxxxxxxxx>
Acked-by: Joerg Roedel <jroedel@xxxxxxx>
Acked-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
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 be22fcf988ce..1467ba1e4417 100644
--- a/drivers/iommu/mtk_iommu_v1.c
+++ b/drivers/iommu/mtk_iommu_v1.c
@@ -425,6 +425,15 @@ 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.
+ * 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",
idx, &iommu_spec)) {