dcd(ip3511): fix DEVCMDSTAT write-1-to-clear handling and EP0 setup races

DEVCMDSTAT mixes read/write fields with write-1-to-clear latches, so a blind
read-modify-write writes a pending latch back as a one and silently clears it -
a setup consumed that way strands EP0. Mask the latches on every update.

The setup path follows the manual's order: acknowledge the latch, then read the
payload. The EP0 IN interrupt is cleared along with EP0 OUT, as the control
endpoint flowchart requires - a control IN completion latched before the setup
must not reach usbd after it, where it would be applied to the request the setup
just started and arm its status stage early.

The payload is copied a byte at a time out of a buffer now declared volatile:
the controller DMAs a new setup packet into it as soon as the latch is cleared,
and C orders volatile accesses only against each other, so gcc sinks a plain
memcpy below the guard read that follows at -O2 and -O3 - leaving only -Os, the
level CI builds, correct.

0 files changed, 0 insertions, 0 deletions