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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Frank Wunderlich <frank-w@public-files.de>,
        Yong Wu <yong.wu@mediatek.com>, Joerg Roedel <jroedel@suse.de>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        Hans Verkuil <hverkuil-cisco@xs4all.nl>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.15 734/913] media: iommu/mediatek-v1: Free the existed fwspec if the master dev already has
Date:   Tue,  5 Apr 2022 09:29:56 +0200
Message-Id: <20220405070401.833508928@linuxfoundation.org>
In-Reply-To: <20220405070339.801210740@linuxfoundation.org>
References: <20220405070339.801210740@linuxfoundation.org>
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From: Yong Wu <yong.wu@mediatek.com>

[ 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>]
(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>
Tested-by: Frank Wunderlich <frank-w@public-files.de> # BPI-R2/MT7623
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Acked-by: Joerg Roedel <jroedel@suse.de>
Acked-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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",
 					   "#iommu-cells",
 					   idx, &iommu_spec)) {
-- 
2.34.1