[PATCH 0/2] iommu: apple-dart: Support the ISP DART

[PATCH 0/2] iommu: apple-dart: Support the ISP DART

[Sasha Finkelstein via B4 Relay]

The ISP block has 3 linked DARTs with mismatched bypass support.
This series adds support for this setup.

(The ISP driver itself is sent as a separate series
https://lore.kernel.org/asahi/20250219-isp-v1-0-6d3e89b67c31@gmail.com/T/ )

Signed-off-by: Sasha Finkelstein <fnkl.kernel@gmail.com>
---
Hector Martin (2):
      iommu: apple-dart: Increase MAX_DARTS_PER_DEVICE to 3
      iommu: apple-dart: Allow mismatched bypass support

 drivers/iommu/apple-dart.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)
---
base-commit: dd83757f6e686a2188997cb58b5975f744bb7786
change-id: 20250227-isp-dart-f8369baaecb1

[PATCH 1/2] iommu: apple-dart: Increase MAX_DARTS_PER_DEVICE to 3

[Sasha Finkelstein via B4 Relay]

From: Hector Martin <marcan@marcan.st>

ISP needs this.

Signed-off-by: Hector Martin <marcan@marcan.st>
Signed-off-by: Sasha Finkelstein <fnkl.kernel@gmail.com>
---
 drivers/iommu/apple-dart.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/apple-dart.c b/drivers/iommu/apple-dart.c
index 95ba3caeb40177901086076416874b9905a1f40a..edb2fb22333506d7c64ad1b6321df00ebfd07747 100644
--- a/drivers/iommu/apple-dart.c
+++ b/drivers/iommu/apple-dart.c
@@ -36,7 +36,7 @@
 
 #define DART_MAX_STREAMS 256
 #define DART_MAX_TTBR 4
-#define MAX_DARTS_PER_DEVICE 2
+#define MAX_DARTS_PER_DEVICE 3
 
 /* Common registers */
 

-- 
2.48.1

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

[Sasha Finkelstein via B4 Relay]

From: Hector Martin <marcan@marcan.st>

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

Signed-off-by: Hector Martin <marcan@marcan.st>
Signed-off-by: Sasha Finkelstein <fnkl.kernel@gmail.com>
---
 drivers/iommu/apple-dart.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/apple-dart.c b/drivers/iommu/apple-dart.c
index edb2fb22333506d7c64ad1b6321df00ebfd07747..a41ad0627be003f2b0ce42a128c3b04bb2537d56 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 +795,25 @@ 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;
 	}
 
+	if (!dart->supports_bypass)
+		cfg->supports_bypass = false;
+
 	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 +953,7 @@ 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;

-- 
2.48.1

Re: [PATCH 2/2] iommu: apple-dart: Allow mismatched bypass support

[Alyssa Rosenzweig]

> +		/* Will be ANDed with DART capabilities */
> +		cfg->supports_bypass = true;
...
> +	if (!dart->supports_bypass)
> +		cfg->supports_bypass = false;

Probably better to write

   cfg->supports_bypass &= dart->supports_bypass;

To match what's in the comment!

Re: [PATCH 1/2] iommu: apple-dart: Increase MAX_DARTS_PER_DEVICE to 3

[Alyssa Rosenzweig]

Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>

Le Thu , Feb 27, 2025 at 05:56:03PM +0100, Sasha Finkelstein via B4 Relay a écrit :
> From: Hector Martin <marcan@marcan.st>
> 
> ISP needs this.
> 
> Signed-off-by: Hector Martin <marcan@marcan.st>
> Signed-off-by: Sasha Finkelstein <fnkl.kernel@gmail.com>
> ---
>  drivers/iommu/apple-dart.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/apple-dart.c b/drivers/iommu/apple-dart.c
> index 95ba3caeb40177901086076416874b9905a1f40a..edb2fb22333506d7c64ad1b6321df00ebfd07747 100644
> --- a/drivers/iommu/apple-dart.c
> +++ b/drivers/iommu/apple-dart.c
> @@ -36,7 +36,7 @@
>  
>  #define DART_MAX_STREAMS 256
>  #define DART_MAX_TTBR 4
> -#define MAX_DARTS_PER_DEVICE 2
> +#define MAX_DARTS_PER_DEVICE 3
>  
>  /* Common registers */
>  
> 
> -- 
> 2.48.1
> 
>