Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Yong Wu <yong.wu@mediatek.com>
To:     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:     Evan Green <evgreen@chromium.org>,
        Robin Murphy <robin.murphy@arm.com>,
        Tomasz Figa <tfiga@chromium.org>,
        Will Deacon <will.deacon@arm.com>,
        <linux-mediatek@lists.infradead.org>,
        <srv_heupstream@mediatek.com>, <devicetree@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <iommu@lists.linux-foundation.org>, <yong.wu@mediatek.com>,
        <youlin.pei@mediatek.com>, Nicolas Boichat <drinkcat@chromium.org>,
        Matthias Kaehlcke <mka@chromium.org>, <anan.sun@mediatek.com>,
        <ming-fan.chen@mediatek.com>, <yi.kuo@mediatek.com>,
        <acourbot@chromium.org>, <linux-media@vger.kernel.org>,
        <dri-devel@lists.freedesktop.org>, Daniel Vetter <daniel@ffwll.ch>,
        Chun-Kuang Hu <chunkuang.hu@kernel.org>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Xia Jiang <xia.jiang@mediatek.com>,
        Tiffany Lin <tiffany.lin@mediatek.com>,
        Dafna Hirschfeld <dafna.hirschfeld@collabora.com>,
        Hsin-Yi Wang <hsinyi@chromium.org>,
        Eizan Miyamoto <eizan@chromium.org>,
        <anthony.huang@mediatek.com>,
        Frank Wunderlich <frank-w@public-files.de>
Subject: [PATCH v7 04/12] iommu/mediatek: Add device_link between the consumer and the larb devices
Date:   Fri, 30 Jul 2021 10:52:30 +0800
Message-ID: <20210730025238.22456-5-yong.wu@mediatek.com>
In-Reply-To: <20210730025238.22456-1-yong.wu@mediatek.com>
References: <20210730025238.22456-1-yong.wu@mediatek.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

MediaTek IOMMU-SMI diagram is like below. all the consumer connect with
smi-larb, then connect with smi-common.

        M4U
         |
    smi-common
         |
  -------------
  |         |    ...
  |         |
larb1     larb2
  |         |
vdec       venc

When the consumer works, it should enable the smi-larb's power which
also need enable the smi-common's power firstly.

Thus, First of all, use the device link connect the consumer and the
smi-larbs. then add device link between the smi-larb and smi-common.

This patch adds device_link between the consumer and the larbs.

When device_link_add, I add the flag DL_FLAG_STATELESS to avoid calling
pm_runtime_xx to keep the original status of clocks. It can avoid two
issues:
1) Display HW show fastlogo abnormally reported in [1]. At the beggining,
all the clocks are enabled before entering kernel, but the clocks for
display HW(always in larb0) will be gated after clk_enable and clk_disable
called from device_link_add(->pm_runtime_resume) and rpm_idle. The clock
operation happened before display driver probe. At that time, the display
HW will be abnormal.

2) A deadlock issue reported in [2]. Use DL_FLAG_STATELESS to skip
pm_runtime_xx to avoid the deadlock.

Corresponding, DL_FLAG_AUTOREMOVE_CONSUMER can't be added, then
device_link_removed should be added explicitly.

[1] https://lore.kernel.org/linux-mediatek/1564213888.22908.4.camel@mhfsdcap03/
[2] https://lore.kernel.org/patchwork/patch/1086569/

Suggested-by: Tomasz Figa <tfiga@chromium.org>
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Tested-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com> # on mt8173
---
 drivers/iommu/mtk_iommu.c    | 22 ++++++++++++++++++++++
 drivers/iommu/mtk_iommu_v1.c | 20 +++++++++++++++++++-
 2 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index a02dde094788..ee742900cf4b 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -571,22 +571,44 @@ static struct iommu_device *mtk_iommu_probe_device(struct device *dev)
 {
 	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
 	struct mtk_iommu_data *data;
+	struct device_link *link;
+	struct device *larbdev;
+	unsigned int larbid;
 
 	if (!fwspec || fwspec->ops != &mtk_iommu_ops)
 		return ERR_PTR(-ENODEV); /* Not a iommu client device */
 
 	data = dev_iommu_priv_get(dev);
 
+	/*
+	 * Link the consumer device with the smi-larb device(supplier)
+	 * The device in each a larb is a independent HW. thus only link
+	 * one larb here.
+	 */
+	larbid = MTK_M4U_TO_LARB(fwspec->ids[0]);
+	larbdev = data->larb_imu[larbid].dev;
+	link = device_link_add(dev, larbdev,
+			       DL_FLAG_PM_RUNTIME | DL_FLAG_STATELESS);
+	if (!link)
+		dev_err(dev, "Unable to link %s\n", dev_name(larbdev));
 	return &data->iommu;
 }
 
 static void mtk_iommu_release_device(struct device *dev)
 {
 	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
+	struct mtk_iommu_data *data;
+	struct device *larbdev;
+	unsigned int larbid;
 
 	if (!fwspec || fwspec->ops != &mtk_iommu_ops)
 		return;
 
+	data = dev_iommu_priv_get(dev);
+	larbid = MTK_M4U_TO_LARB(fwspec->ids[0]);
+	larbdev = data->larb_imu[larbid].dev;
+	device_link_remove(dev, larbdev);
+
 	iommu_fwspec_free(dev);
 }
 
diff --git a/drivers/iommu/mtk_iommu_v1.c b/drivers/iommu/mtk_iommu_v1.c
index c259433f1130..806d4200665b 100644
--- a/drivers/iommu/mtk_iommu_v1.c
+++ b/drivers/iommu/mtk_iommu_v1.c
@@ -424,7 +424,9 @@ static struct iommu_device *mtk_iommu_probe_device(struct device *dev)
 	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
 	struct of_phandle_args iommu_spec;
 	struct mtk_iommu_data *data;
-	int err, idx = 0;
+	int err, idx = 0, larbid;
+	struct device_link *link;
+	struct device *larbdev;
 
 	/*
 	 * In the deferred case, free the existed fwspec if the dev already has,
@@ -454,6 +456,14 @@ static struct iommu_device *mtk_iommu_probe_device(struct device *dev)
 
 	data = dev_iommu_priv_get(dev);
 
+	/* Link the consumer device with the smi-larb device(supplier) */
+	larbid = mt2701_m4u_to_larb(fwspec->ids[0]);
+	larbdev = data->larb_imu[larbid].dev;
+	link = device_link_add(dev, larbdev,
+			       DL_FLAG_PM_RUNTIME | DL_FLAG_STATELESS);
+	if (!link)
+		dev_err(dev, "Unable to link %s\n", dev_name(larbdev));
+
 	return &data->iommu;
 }
 
@@ -474,10 +484,18 @@ static void mtk_iommu_probe_finalize(struct device *dev)
 static void mtk_iommu_release_device(struct device *dev)
 {
 	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
+	struct mtk_iommu_data *data;
+	struct device *larbdev;
+	unsigned int larbid;
 
 	if (!fwspec || fwspec->ops != &mtk_iommu_ops)
 		return;
 
+	data = dev_iommu_priv_get(dev);
+	larbid = mt2701_m4u_to_larb(fwspec->ids[0]);
+	larbdev = data->larb_imu[larbid].dev;
+	device_link_remove(dev, larbdev);
+
 	iommu_fwspec_free(dev);
 }
 
-- 
2.18.0