[v3,2/2] iommu: apple-dart: Allow mismatched bypass support

Commit Message

Sasha Finkelstein via B4 Relay March 7, 2025, 8:07 p.m. UTC

From: Hector Martin <[e-mail]>

This is needed by ISP, which has DART0 with bypass and DART1/2 without.

Signed-off-by: Hector Martin <[e-mail]>
Reviewed-by: Alyssa Rosenzweig <[e-mail]>
Signed-off-by: Sasha Finkelstein <[e-mail]>
---
 drivers/iommu/apple-dart.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

Patch

diff --git a/drivers/iommu/apple-dart.c b/drivers/iommu/apple-dart.c
index edb2fb22333506d7c64ad1b6321df00ebfd07747..13ccb801f52a4d34f6653f78e92787af7dfed1bc 100644
--- a/drivers/iommu/apple-dart.c
+++ b/drivers/iommu/apple-dart.c
@@ -277,6 +277,9 @@  struct apple_dart_domain {
  * @streams: streams for this device
  */
 struct apple_dart_master_cfg {
+	/* Intersection of DART capabilitles */
+	u32 supports_bypass : 1;
+
 	struct apple_dart_stream_map stream_maps[MAX_DARTS_PER_DEVICE];
 };
 
@@ -684,7 +687,7 @@  static int apple_dart_attach_dev_identity(struct iommu_domain *domain,
 	struct apple_dart_stream_map *stream_map;
 	int i;
 
-	if (!cfg->stream_maps[0].dart->supports_bypass)
+	if (!cfg->supports_bypass)
 		return -EINVAL;
 
 	for_each_stream_map(i, cfg, stream_map)
@@ -792,20 +795,24 @@  static int apple_dart_of_xlate(struct device *dev,
 		return -EINVAL;
 	sid = args->args[0];
 
-	if (!cfg)
+	if (!cfg) {
 		cfg = kzalloc(sizeof(*cfg), GFP_KERNEL);
+
+		/* Will be ANDed with DART capabilities */
+		cfg->supports_bypass = true;
+	}
 	if (!cfg)
 		return -ENOMEM;
 	dev_iommu_priv_set(dev, cfg);
 
 	cfg_dart = cfg->stream_maps[0].dart;
 	if (cfg_dart) {
-		if (cfg_dart->supports_bypass != dart->supports_bypass)
-			return -EINVAL;
 		if (cfg_dart->pgsize != dart->pgsize)
 			return -EINVAL;
 	}
 
+	cfg->supports_bypass &= dart->supports_bypass;
+
 	for (i = 0; i < MAX_DARTS_PER_DEVICE; ++i) {
 		if (cfg->stream_maps[i].dart == dart) {
 			set_bit(sid, cfg->stream_maps[i].sidmap);
@@ -945,7 +952,7 @@  static int apple_dart_def_domain_type(struct device *dev)
 
 	if (cfg->stream_maps[0].dart->pgsize > PAGE_SIZE)
 		return IOMMU_DOMAIN_IDENTITY;
-	if (!cfg->stream_maps[0].dart->supports_bypass)
+	if (!cfg->supports_bypass)
 		return IOMMU_DOMAIN_DMA;
 
 	return 0;