[PATCH v2 08/13] iommu/mtk: Constrain return value of ->attach_dev()

[Nicolin Chen]

Ensure attach_dev() callback functions only return errno values expected
from the attach_dev() op. In particular, only return -EINVAL when we are
sure that the device is incompatible with the domain.

Also drop any dev_err next to -EINVAL, following the attach_dev op kdocs.

Signed-off-by: Nicolin Chen <nicolinc at nvidia.com>
---
 drivers/iommu/mtk_iommu.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index 7e363b1f24df..78c31b307ee1 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -655,7 +655,7 @@ static int mtk_iommu_attach_device(struct iommu_domain *domain,
 
 	region_id = mtk_iommu_get_iova_region_id(dev, data->plat_data);
 	if (region_id < 0)
-		return region_id;
+		return -ENODEV;
 
 	bankid = mtk_iommu_get_bank_id(dev, data->plat_data);
 	mutex_lock(&dom->mutex);
@@ -678,12 +678,14 @@ static int mtk_iommu_attach_device(struct iommu_domain *domain,
 		ret = pm_runtime_resume_and_get(m4udev);
 		if (ret < 0) {
 			dev_err(m4udev, "pm get fail(%d) in attach.\n", ret);
+			ret = -ENODEV;
 			goto err_unlock;
 		}
 
 		ret = mtk_iommu_hw_init(data, bankid);
 		if (ret) {
 			pm_runtime_put(m4udev);
+			ret = -ENODEV;
 			goto err_unlock;
 		}
 		bank->m4u_dom = dom;
@@ -693,7 +695,10 @@ static int mtk_iommu_attach_device(struct iommu_domain *domain,
 	}
 	mutex_unlock(&data->mutex);
 
-	return mtk_iommu_config(data, dev, true, region_id);
+	ret = mtk_iommu_config(data, dev, true, region_id);
+	if (ret)
+		ret = -ENODEV;
+	return ret;
 
 err_unlock:
 	mutex_unlock(&data->mutex);
-- 
2.17.1