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Subject[PATCH v3 03/14] iommu/mediatek: Add device_link between the consumer and the larb devices
Date
MediaTek IOMMU don't have its power-domain. 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] http://lists.infradead.org/pipermail/linux-mediatek/2019-July/
021500.html
[2] https://lore.kernel.org/patchwork/patch/1086569/

Suggested-by: Tomasz Figa <tfiga@chromium.org>
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
---
drivers/iommu/mtk_iommu.c | 17 +++++++++++++++++
drivers/iommu/mtk_iommu_v1.c | 18 +++++++++++++++++-
2 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index b138b94..2511b3c 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -450,6 +450,9 @@ static int mtk_iommu_add_device(struct device *dev)
struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
struct mtk_iommu_data *data;
struct iommu_group *group;
+ struct device_link *link;
+ struct device *larbdev;
+ unsigned int larbid;

if (!fwspec || fwspec->ops != &mtk_iommu_ops)
return -ENODEV; /* Not a iommu client device */
@@ -461,6 +464,14 @@ static int mtk_iommu_add_device(struct device *dev)
if (IS_ERR(group))
return PTR_ERR(group);

+ /* Link the consumer device with the smi-larb device(supplier) */
+ 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));
+
iommu_group_put(group);
return 0;
}
@@ -469,6 +480,8 @@ static void mtk_iommu_remove_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;
@@ -476,6 +489,10 @@ static void mtk_iommu_remove_device(struct device *dev)
data = fwspec->iommu_priv;
iommu_device_unlink(&data->iommu, dev);

+ larbid = MTK_M4U_TO_LARB(fwspec->ids[0]);
+ larbdev = data->larb_imu[larbid].dev;
+ device_link_remove(dev, larbdev);
+
iommu_group_remove_device(dev);
iommu_fwspec_free(dev);
}
diff --git a/drivers/iommu/mtk_iommu_v1.c b/drivers/iommu/mtk_iommu_v1.c
index 2034d72..a7f22a2 100644
--- a/drivers/iommu/mtk_iommu_v1.c
+++ b/drivers/iommu/mtk_iommu_v1.c
@@ -423,7 +423,9 @@ static int mtk_iommu_add_device(struct device *dev)
struct of_phandle_iterator it;
struct mtk_iommu_data *data;
struct iommu_group *group;
- int err;
+ struct device_link *link;
+ struct device *larbdev;
+ int err, larbid;

of_for_each_phandle(&it, err, dev->of_node, "iommus",
"#iommu-cells", 0) {
@@ -466,6 +468,14 @@ static int mtk_iommu_add_device(struct device *dev)
return err;
}

+ /* 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 iommu_device_link(&data->iommu, dev);
}

@@ -473,6 +483,8 @@ static void mtk_iommu_remove_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;
@@ -480,6 +492,10 @@ static void mtk_iommu_remove_device(struct device *dev)
data = fwspec->iommu_priv;
iommu_device_unlink(&data->iommu, dev);

+ larbid = mt2701_m4u_to_larb(fwspec->ids[0]);
+ larbdev = data->larb_imu[larbid].dev;
+ device_link_remove(dev, larbdev);
+
iommu_group_remove_device(dev);
iommu_fwspec_free(dev);
}
--
1.9.1
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