[PATCH REGRESSION v2] iommu/apple-dart: Handle DMA_FQ domains in attach_dev()

[Hector Martin]

Commit a4fdd9762272 ("iommu: Use flush queue capability") hid the
IOMMU_DOMAIN_DMA_FQ domain type from domain allocation. A check was
introduced in iommu_dma_init_domain() to fall back if not supported, but
this check runs too late: by that point, devices have been attached to
the IOMMU, and apple-dart's attach_dev() callback does not expect
IOMMU_DOMAIN_DMA_FQ domains.

Change the logic so the IOMMU_DOMAIN_DMA codepath is the default,
instead of explicitly enumerating all types.

Fixes an apple-dart regression in v6.5.

Cc: regressions@xxxxxxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
Suggested-by: Robin Murphy <robin.murphy@xxxxxxx>
Fixes: a4fdd9762272 ("iommu: Use flush queue capability")
Signed-off-by: Hector Martin <marcan@xxxxxxxxx>
---
Changes in v2:
- Fixed the issue in apple-dart instead of the iommu core, per Robin's
  suggestion.
- Link to v1: https://lore.kernel.org/r/20230922-iommu-type-regression-v1-1-1ed3825b2c38@xxxxxxxxx
---
 drivers/iommu/apple-dart.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/iommu/apple-dart.c b/drivers/iommu/apple-dart.c
index 2082081402d3..0b8927508427 100644
--- a/drivers/iommu/apple-dart.c
+++ b/drivers/iommu/apple-dart.c
@@ -671,8 +671,7 @@ static int apple_dart_attach_dev(struct iommu_domain *domain,
 		return ret;
 
 	switch (domain->type) {
-	case IOMMU_DOMAIN_DMA:
-	case IOMMU_DOMAIN_UNMANAGED:
+	default:
 		ret = apple_dart_domain_add_streams(dart_domain, cfg);
 		if (ret)
 			return ret;

---
base-commit: ce9ecca0238b140b88f43859b211c9fdfd8e5b70
change-id: 20230922-iommu-type-regression-25b4f43df770

Best regards,
-- 
Hector Martin <marcan@xxxxxxxxx>