On Wed, 2021-09-29 at 18:33 +0200, Dafna Hirschfeld wrote:

On 29.09.21 03:37, Yong Wu wrote:

quoted

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 consumers always are 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.

device_is_bound may be more elegant here. but it is not allowed to
EXPORT from https://lore.kernel.org/patchwork/patch/1334670/.

Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Tested-by: Frank Wunderlich <redacted> # BPI-
R2/MT7623
---
  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 d837adfd1da5..d5848f78a677 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c

@@ -844,7 +844,7 @@ 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;

if plarbdev is null doesn't that mean that the device does not exist?

This is probe function, Is it possible the platform device is not ready
at this time?

I checked the platform device should be created at:

of_platform_default_populate_init:  arch_initcall_sync
  ->of_platform_populate
      ->of_platform_device_create_pdata

Not sure if this may be delayed for some device. If not, it should be
ENODEV here.

so we should return -ENODEV in that case?

thanks,
Dafna

quoted

  		}

diff --git a/drivers/iommu/mtk_iommu_v1.c

b/drivers/iommu/mtk_iommu_v1.c
index 1467ba1e4417..4d7809432239 100644

--- a/drivers/iommu/mtk_iommu_v1.c
+++ b/drivers/iommu/mtk_iommu_v1.c

@@ -602,7 +602,7 @@ 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;
  		}

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