linux-kernel - [PATCH v6 02/11] iommu/mediatek: Add probe

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Date:   Wed, 14 Jul 2021 10:56:17 +0800
From:   Yong Wu <yong.wu@...iatek.com>
To:     Matthias Brugger <matthias.bgg@...il.com>,
        Joerg Roedel <joro@...tes.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        David Airlie <airlied@...ux.ie>,
        Mauro Carvalho Chehab <mchehab@...nel.org>
CC:     Evan Green <evgreen@...omium.org>,
        Robin Murphy <robin.murphy@....com>,
        Tomasz Figa <tfiga@...omium.org>,
        Will Deacon <will.deacon@....com>,
        <linux-mediatek@...ts.infradead.org>,
        <srv_heupstream@...iatek.com>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <iommu@...ts.linux-foundation.org>, <yong.wu@...iatek.com>,
        <youlin.pei@...iatek.com>, Nicolas Boichat <drinkcat@...omium.org>,
        Matthias Kaehlcke <mka@...omium.org>, <anan.sun@...iatek.com>,
        <ming-fan.chen@...iatek.com>, <yi.kuo@...iatek.com>,
        <acourbot@...omium.org>, <linux-media@...r.kernel.org>,
        <dri-devel@...ts.freedesktop.org>, Daniel Vetter <daniel@...ll.ch>,
        Chun-Kuang Hu <chunkuang.hu@...nel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Xia Jiang <xia.jiang@...iatek.com>,
        Tiffany Lin <tiffany.lin@...iatek.com>,
        Dafna Hirschfeld <dafna.hirschfeld@...labora.com>,
        Hsin-Yi Wang <hsinyi@...omium.org>,
        Eizan Miyamoto <eizan@...omium.org>,
        <anthony.huang@...iatek.com>
Subject: [PATCH v6 02/11] iommu/mediatek: Add probe_defer for smi-larb

Prepare for adding device_link.

The iommu consumer should use device_link to connect with the
smi-larb(supplier). then the smi-larb should run before the iommu
consumer. Here we delay the iommu driver until the smi driver is
ready, then all the iommu consumer always is after the smi driver.

When there is no this patch, if some consumer drivers run before
smi-larb, the supplier link_status is DL_DEV_NO_DRIVER(0) in the
device_link_add, then device_links_driver_bound will use WARN_ON
to complain that the link_status of supplier is not right.

Signed-off-by: Yong Wu <yong.wu@...iatek.com>
---
since [1], device_is_bound is not allowed to be EXPORT. It will
affect this driver built as module. thus still use dev.driver here.

[1] https://lore.kernel.org/patchwork/patch/1334670/
---
 drivers/iommu/mtk_iommu.c    | 2 +-
 drivers/iommu/mtk_iommu_v1.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index 6f7c69688ce2..a02dde094788 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -855,7 +855,7 @@ static int mtk_iommu_probe(struct platform_device *pdev)
 			id = i;
 
 		plarbdev = of_find_device_by_node(larbnode);
-		if (!plarbdev) {
+		if (!plarbdev || !plarbdev->dev.driver) {
 			of_node_put(larbnode);
 			return -EPROBE_DEFER;
 		}
diff --git a/drivers/iommu/mtk_iommu_v1.c b/drivers/iommu/mtk_iommu_v1.c
index 778e66f5f1aa..d9365a3d8dc9 100644
--- a/drivers/iommu/mtk_iommu_v1.c
+++ b/drivers/iommu/mtk_iommu_v1.c
@@ -594,7 +594,7 @@ static int mtk_iommu_probe(struct platform_device *pdev)
 		}
 
 		plarbdev = of_find_device_by_node(larbnode);
-		if (!plarbdev) {
+		if (!plarbdev || !plarbdev->dev.driver) {
 			of_node_put(larbnode);
 			return -EPROBE_DEFER;
 		}
-- 
2.18.0