On Wed, Feb 12, 2025 at 03:21:46PM -0600, Rob Herring wrote:

[...]

quoted

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+  - If the kernel is entered at EL1 and EL2 is present:
+
+    - BRBCR_EL2.CC (bit 3) must be initialised to 0b1.
+    - BRBCR_EL2.MPRED (bit 4) must be initialised to 0b1.

Should clarify BRBCR_EL2.TS to be initialised to 0b00 ?  Arm ARM
claims the reset behaviour of the TS field is unknown value.  The
assembly code below actually has initializes the TS field as zero.

Humm, we don't currently care what it is initialized to because the
timestamp is never used. We would care in the future if we use
timestamps. Will 0b00 be the only correct value? I'm not sure.

In initializaton phase, if set BRBCR_EL2.TS = 0b00, then the timestamp
will be decided by BRBCR_EL1.TS.  I expect the BRBE driver will always
write BRBCR_EL1.TS.

Thanks,
Leo