From: Levi Yun <yeoreum.yun@arm.com>

UUID is saved in big endian format.
i.e) For uuid "378daedc-f06b-4446-8314-40ab933c87a3",

It should be saved in memory like:
    37 8d ae dc
    f0 6b 44 46
    83 14 40 ab
    93 3c 87 a3

Accoding to FF-A specification[0] 15.4 FFA_MSG_SEND_DRIECT_REQ2,
then UUID is saved in register:
    UUID Lo  x2  Bytes[0...7] of UUID with byte 0 in the low-order bits.
    UUID Hi  x3  Bytes[8...15] of UUID with byte 8 in the low-order bits.

That means, we don't need to swap the uuid when it send via direct
message request version 2, just send it as saved in memory.

Remove le64_to_cpu() for uuid in direct message request version 2,
and change uuid_regs' type to __be64 because UUID is saved in network
byte order.

Link: https://developer.arm.com/documentation/den0077/latest [0]
Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
---
 drivers/firmware/arm_ffa/driver.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/driver.c
index a3a9cdec7389..4a6bc6520d25 100644
--- a/drivers/firmware/arm_ffa/driver.c
+++ b/drivers/firmware/arm_ffa/driver.c
@@ -483,13 +483,13 @@ static int ffa_msg_send_direct_req2(u16 src_id, u16 dst_id, const uuid_t *uuid,
 	u32 src_dst_ids = PACK_TARGET_INFO(src_id, dst_id);
 	union {
 		uuid_t uuid;
-		__le64 regs[2];
+		__be64 regs[2];
 	} uuid_regs = { .uuid = *uuid };
 	ffa_value_t ret, args = {
 		.a0 = FFA_MSG_SEND_DIRECT_REQ2,
 		.a1 = src_dst_ids,
-		.a2 = le64_to_cpu(uuid_regs.regs[0]),
-		.a3 = le64_to_cpu(uuid_regs.regs[1]),
+		.a2 = uuid_regs.regs[0],
+		.a3 = uuid_regs.regs[1],
 	};
 	memcpy((void *)&args + offsetof(ffa_value_t, a4), data, sizeof(*data));
 
-- 
LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}

On Mon, Nov 25, 2024 at 09:52:51AM +0000, Yeoreum Yun wrote:
> From: Levi Yun <yeoreum.yun@arm.com>
> 
> UUID is saved in big endian format.
> i.e) For uuid "378daedc-f06b-4446-8314-40ab933c87a3",
> 
> It should be saved in memory like:
>     37 8d ae dc
>     f0 6b 44 46
>     83 14 40 ab
>     93 3c 87 a3
> 
> Accoding to FF-A specification[0] 15.4 FFA_MSG_SEND_DRIECT_REQ2,
> then UUID is saved in register:
>     UUID Lo  x2  Bytes[0...7] of UUID with byte 0 in the low-order bits.
>     UUID Hi  x3  Bytes[8...15] of UUID with byte 8 in the low-order bits.
> 
> That means, we don't need to swap the uuid when it send via direct
> message request version 2, just send it as saved in memory.
> 
> Remove le64_to_cpu() for uuid in direct message request version 2,
> and change uuid_regs' type to __be64 because UUID is saved in network
> byte order.
>

  |   warning: incorrect type in initializer (different base types)
  |      expected unsigned long a2
  |      got restricted __be64
  |   warning: incorrect type in initializer (different base types)
  |      expected unsigned long a3
  |      got restricted __be64

We will get this warning back with this change, wondering if we can take
up BE support separately.

--
Regards,
Sudeep

Hi, Sudeep.
>
>   |   warning: incorrect type in initializer (different base types)
>   |      expected unsigned long a2
>   |      got restricted __be64
>   |   warning: incorrect type in initializer (different base types)
>   |      expected unsigned long a3
>   |      got restricted __be64
>
> We will get this warning back with this change, wondering if we can take
> up BE support separately.

Sorry. I'll change the type :\ Thanks to let me know!