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Subject: Re: [PATCH v9 02/15] iommu/mediatek-v1: Free the existed fwspec if
 the master dev already has
To:     Yong Wu <yong.wu@mediatek.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Joerg Roedel <joro@8bytes.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>,
        David Airlie <airlied@linux.ie>,
        Mauro Carvalho Chehab <mchehab@kernel.org>
Cc:     Dafna Hirschfeld <dafna.hirschfeld@collabora.com>,
        Chun-Kuang Hu <chunkuang.hu@kernel.org>,
        Will Deacon <will.deacon@arm.com>,
        dri-devel@lists.freedesktop.org, yf.wang@mediatek.com,
        anthony.huang@mediatek.com, youlin.pei@mediatek.com,
        Evan Green <evgreen@chromium.org>,
        Eizan Miyamoto <eizan@chromium.org>,
        Matthias Kaehlcke <mka@chromium.org>,
        linux-arm-kernel@lists.infradead.org, mingyuan.ma@mediatek.com,
        linux-media@vger.kernel.org, devicetree@vger.kernel.org,
        Philipp Zabel <p.zabel@pengutronix.de>, libo.kang@mediatek.com,
        yi.kuo@mediatek.com, linux-mediatek@lists.infradead.org,
        Hsin-Yi Wang <hsinyi@chromium.org>,
        Tiffany Lin <tiffany.lin@mediatek.com>, anan.sun@mediatek.com,
        srv_heupstream@mediatek.com, acourbot@chromium.org,
        linux-kernel@vger.kernel.org, Tomasz Figa <tfiga@chromium.org>,
        iommu@lists.linux-foundation.org, Daniel Vetter <daniel@ffwll.ch>,
        Robin Murphy <robin.murphy@arm.com>
References: <20211112105509.12010-1-yong.wu@mediatek.com>
 <20211112105509.12010-3-yong.wu@mediatek.com>
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>
Message-ID: <db984e48-a0fc-0802-0ce6-69d542c08771@collabora.com>
Date:   Tue, 11 Jan 2022 11:57:51 +0100
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Il 12/11/21 11:54, Yong Wu ha scritto:
> 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: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>