Diagnostic scaffolding kept from chasing the "screen flashes teal on every
message" report, behind -DTDP4_FLUSH_TRACE so it is compiled out of normal
builds (verified: no FLUSHTRACE string in the shipped binary).
It logs any large, mostly-single-colour flush band with its RGB565 value. That
answers the one question that was otherwise unanswerable from the outside: is
the flash something LVGL painted, or something below it? A UI-painted flash
appears as a burst of bands carrying that colour; if the screen visibly flashes
and nothing logs, the cause is in the panel/DSI layer and hunting through UI
widgets is wasted effort.
Two notes recorded in the comment because both cost time here. One LVGL band on
this board is 284x24 = 6816 px, so a size gate has to sit well below that — an
earlier 8000 px threshold silently disabled the whole tracer and looked like
"nothing is drawing". And the per-band uniformity scan measurably slows the
flush path, so it can mask a timing-sensitive bug: any fix must be confirmed on
a build with the tracer OFF.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
