On Mon, Aug 14, 2023 at 02:44:50PM +0800, Baolu Lu wrote:

On 2023/8/3 8:08, Jason Gunthorpe wrote:

quoted

Prior to commit 1b932ceddd19 ("iommu: Remove detach_dev callbacks") the
sun50i_iommu_detach_device() function was being called by
ops->detach_dev().

This is an IDENTITY domain so convert sun50i_iommu_detach_device() into
sun50i_iommu_identity_attach() and a full IDENTITY domain and thus hook it
back up the same was as the old ops->detach_dev().

Signed-off-by: Jason Gunthorpe<jgg@nvidia.com>
---
  drivers/iommu/sun50i-iommu.c | 26 +++++++++++++++++++-------
  1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/drivers/iommu/sun50i-iommu.c b/drivers/iommu/sun50i-iommu.c
index 74c5cb93e90027..0bf08b120cf105 100644
--- a/drivers/iommu/sun50i-iommu.c
+++ b/drivers/iommu/sun50i-iommu.c

@@ -757,21 +757,32 @@ static void sun50i_iommu_detach_domain(struct sun50i_iommu *iommu,
  	iommu->domain = NULL;
  }
-static void sun50i_iommu_detach_device(struct iommu_domain *domain,
-				       struct device *dev)
+static int sun50i_iommu_identity_attach(struct iommu_domain *identity_domain,
+					struct device *dev)
  {
-	struct sun50i_iommu_domain *sun50i_domain = to_sun50i_domain(domain);
  	struct sun50i_iommu *iommu = dev_iommu_priv_get(dev);
+	struct sun50i_iommu_domain *sun50i_domain;
  	dev_dbg(dev, "Detaching from IOMMU domain\n");
-	if (iommu->domain != domain)
-		return;
+	if (iommu->domain == identity_domain)
+		return 0;
+	sun50i_domain = to_sun50i_domain(iommu->domain);
  	if (refcount_dec_and_test(&sun50i_domain->refcnt))
  		sun50i_iommu_detach_domain(iommu, sun50i_domain);
+	return 0;
  }

Does iommu->domain need to be set to identity_domain before returning?

sun50i_iommu_detach_domain() does it.

This driver is confused because it uses generic_single_device_group
but also has this weird refcounting stuff. It should just make the
first attach alter the HW and have the remaining ones (eg new domain
== current domani) be NOPs. It should not refcount.

Jason

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