mailbox: mpfs-mbox: replace unbounded BUSY polling with bounded waits

The MPFS mailbox driver used unbounded polling loops and treated the
BUSY bit as a fatal condition in several paths. On MPFS, BUSY may be
transiently reasserted even after response data is written, which is
observable in U-Boot’s synchronous, polled execution model.

Replace the unbounded loops with a bounded
regmap_read_poll_timeout()-based helper that waits for the controller to
become idle.

This preserves existing behaviour while preventing infinite stalls
and avoiding spurious failures during early boot.

Signed-off-by: Jamie Gibbons <[email protected]>
Reviewed-by: Conor Dooley <[email protected]>

0 files changed, 0 insertions, 0 deletions