[PATCH] perf python: Fix arm-cs-trace-disasm type error

[James Clark]

The perf sample dso_bid getter returns a string or None, matching its
Optional[str] annotation. Attempting to decode it as bytes causes mypy
to report union-attr errors, even though this was behind a conditional
that checked for bytes type.

Use the string directly, retaining the fallback for an unknown build ID.

This fixes the following build error:

  python/arm-cs-trace-disasm.py:266: error: Item "None" of "str | None" has no attribute "decode"  [union-attr]

Fixes: 279b402e5143 ("perf python: Port arm-cs-trace-disasm to perf module")
Assisted-by: Codex:GPT-6-Astra
Signed-off-by: James Clark <james.clark@xxxxxxxxxx>
---
 tools/perf/python/arm-cs-trace-disasm.py | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/tools/perf/python/arm-cs-trace-disasm.py b/tools/perf/python/arm-cs-trace-disasm.py
index cf126ac79c18..1812ccaf4b20 100755
--- a/tools/perf/python/arm-cs-trace-disasm.py
+++ b/tools/perf/python/arm-cs-trace-disasm.py
@@ -263,9 +263,7 @@ class TraceDisasm:
 
         dso = getattr(sample, 'dso_long_name', None) or sample.dso or '[unknown]'
         symbol = sample.symbol or '[unknown]'
-        dso_bid = (sample.dso_bid.decode('utf-8')
-                   if isinstance(sample.dso_bid, bytes)
-                   else str(sample.dso_bid or '[unknown]'))
+        dso_bid = sample.dso_bid or '[unknown]'
         dso_start = sample.map_start
         dso_end = sample.map_end
         map_pgoff = sample.map_pgoff or 0

---
base-commit: 0ae6fc78c5ce0dfd18d8712a50f0fd4602eff103
change-id: 20260928-james-perf-mypy-cs-disasm-ed5ab0b60a8a

Best regards,
--  
James Clark <james.clark@xxxxxxxxxx>