On 16.08.25 16:19, Janne Grunau wrote:

Hej,

On Sat, Aug 16, 2025, at 15:50, Sven Peter wrote:

quoted

On 14.08.25 10:40, Janne Grunau wrote:

quoted

From: Hector Martin <redacted>

The T8110 variant DART implementation on T602x SoCs indicates an IAS
of 42, which requires an extra page table level. The extra level is
optional, but let's implement it.

Since the driver failed at IO page table creation with 42-bit IAS add
"apple,t6020-dart" as separate compatible using the T8110 HW data.

Is the commit description outdated? I don't see this change anywhere.

yes, I decided to handle this as missing feature / bug. Both end up with
the same result and as far as we can tell it is fully compatible.
Removed locally.

quoted

quoted

Later it might be useful to restrict this based on the actual
attached devices, since most won't need that much address space
anyway.

Signed-off-by: Hector Martin <redacted> Signed-off-by: Janne
Grunau [off-list ref]
---
   drivers/iommu/apple-dart.c | 23 +++++++++++++++++------ 1 file
   changed, 17 insertions(+), 6 deletions(-)

diff --git a/drivers/iommu/apple-dart.c b/drivers/iommu/apple-dart.c
index e72a93e78e26ca61b233c83d439dbdfadf040fc6..bb48e8603d6c84bcf107-

294d851c2f2fc1273298 100644 --- a/drivers/iommu/apple-dart.c +++ b/drivers/iommu/apple-
dart.c @@ -133,6 +133,7 @@  #define DART_T8110_TCR
0x1000  #define DART_T8110_TCR_REMAP            GENMASK(11, 8)
#define DART_T8110_TCR_REMAP_EN         BIT(7) +#define
DART_T8110_TCR_FOUR_LEVEL       BIT(3)  #define
DART_T8110_TCR_BYPASS_DAPF      BIT(2)  #define
DART_T8110_TCR_BYPASS_DART      BIT(1)  #define
DART_T8110_TCR_TRANSLATE_ENABLE BIT(0) @@ -177,6 +178,7 @@ struct
apple_dart_hw {     u32 tcr_enabled;     u32 tcr_disabled;     u32
tcr_bypass;
+    u32 tcr_4level;

      u32 ttbr; u32 ttbr_valid; @@ -217,6 +219,7 @@ struct apple_dart
      { u32 pgsize; u32 num_streams; u32 supports_bypass : 1;
+    u32 four_level : 1;

      struct iommu_group *sid2group[DART_MAX_STREAMS]; struct
      iommu_device iommu; @@ -305,13 +308,16 @@ static struct
      apple_dart_domain *to_dart_domain(struct iommu_domain *dom) }

   static void -apple_dart_hw_enable_translation(struct
   apple_dart_stream_map *stream_map)
   +apple_dart_hw_enable_translation(struct apple_dart_stream_map
   *stream_map, int levels) {   struct apple_dart *dart = stream_map-
   >dart;   int sid;

+    WARN_ON(levels != 3 && levels != 4);
+    WARN_ON(levels == 4 && !dart->four_level); for_each_set_bit(sid,
      stream_map->sidmap, dart->num_streams)
-            writel(dart->hw->tcr_enabled, dart->regs +
              DART_TCR(dart, sid));
+            writel(dart->hw->tcr_enabled | (levels == 4 ? dart->hw-
              >tcr_4level : 0),
+                   dart->regs + DART_TCR(dart, sid));

This is a bit hard to read, I'd prefer an explicit if (dart->hw-

quoted

tcr_4level) here.

you mean `if (levels == 4)`? `dart->hw->tcr_4level` will be `BIT(3)` for
t8110 darts even when they use just 3 page table levels.

yup, I must've copy/pasted the wrong thing.

Changed locally to

u32 tcr = dart->hw->tcr_enabled; if (levels == 4)        tcr |= dart->hw-

quoted

tcr_4level;

and then writel(tcr, ...) in the loop.

Great, I didn't even realize you could move that entire thing out of the 
loop.

I've change prefix of all commits in this series to "iommu/apple-dart"
and "iommu/io-pgtable-dart".

Feel free to add my Reviewed-by for this commit as well then.



Thanks,

Sven