[PATCH AUTOSEL 5.16 13/59] media: iommu/mediatek: Add device_link between the consumer and the larb devices

Sasha Levin
2022-03-30T11:57:12Z

From: Yong Wu <yong.wu@mediatek.com>

[ Upstream commit 635319a4a7444ca97124d781cd96deb277ff4d40 ]

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.

Meanwhile, Currently we don't have a device connect with 2 larbs at the
same time. Disallow this case, print the error log.

[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: Frank Wunderlich <frank-w@public-files.de> # BPI-R2/MT7623
Acked-by: Joerg Roedel <jroedel@suse.de>
Reviewed-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.c | 30 ++++++++++++++++++++++++++++++
drivers/iommu/mtk_iommu_v1.c | 29 ++++++++++++++++++++++++++++-
2 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index 77ae20ff9b35..5971a1168666 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -562,22 +562,52 @@ 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, larbidx, i;

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 that connects with each a larb is a independent HW.
+ * All the ports in each a device should be in the same larbs.
+ */
+ larbid = MTK_M4U_TO_LARB(fwspec->ids[0]);
+ for (i = 1; i < fwspec->num_ids; i++) {
+ larbidx = MTK_M4U_TO_LARB(fwspec->ids[i]);
+ if (larbid != larbidx) {
+ dev_err(dev, "Can only use one larb. Fail@larb%d-%d.\n",
+ larbid, larbidx);
+ return ERR_PTR(-EINVAL);
+ }
+ }
+ 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 68bf02f87cfd..bc7ee90b9373 100644
--- a/drivers/iommu/mtk_iommu_v1.c
+++ b/drivers/iommu/mtk_iommu_v1.c
@@ -423,7 +423,9 @@ 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, larbidx;
+ struct device_link *link;
+ struct device *larbdev;

/*
* In the deferred case, free the existed fwspec.
@@ -453,6 +455,23 @@ 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]);
+ for (idx = 1; idx < fwspec->num_ids; idx++) {
+ larbidx = mt2701_m4u_to_larb(fwspec->ids[idx]);
+ if (larbid != larbidx) {
+ dev_err(dev, "Can only use one larb. Fail@larb%d-%d.\n",
+ larbid, larbidx);
+ return ERR_PTR(-EINVAL);
+ }
+ }
+
+ 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;
}

@@ -473,10 +492,18 @@ 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);
}

--
2.34.1