[PATCH 0/4] Fix transmit handling on SCI/RSCI ports

[Biju]

From: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>

Hi All,

This series fixes several transmit problems on the SCI (PORT_SCI) and
RSCI ports of the sh-sci driver, seen on Renesas RZ SoCs:

 - Patch 1 removes the code that disables TE at the end of a
   transmission on SCI, which the hardware manual does not describe.
 - Patch 2 stops the TEI handler from turning the transmitter off
   while the xmit kfifo still holds data, which could stall or lose
   output. It also covers the TE handling that patch 1 no longer does
   in sci_transmit_chars().
 - Patch 3 skips the software clear of the TDxE flag on SCI, since
   hardware clears it on a TDR write and the extra clear caused a
   spurious TXI and a duplicated last character.
 - Patch 4 forces a TE toggle when restoring SCSCR in the console
   write path on SCI, so the TXI that restarts an interrupted drain is
   generated. Without it the RZ/G2UL console can hang during boot.

Au Dang (2):
  serial: sh-sci: Skip TDxE status clear for PORT_SCI
  serial: sh-sci: Toggle TE when restoring SCSCR in console write on SCI

Biju Das (2):
  serial: sh-sci: Drop TE disable at end of transmission on SCI
  serial: sh-sci: Don’t disable TX on TEI while the xmit kfifo still
    holds data

 drivers/tty/serial/rsci.c          |  2 ++
 drivers/tty/serial/sh-sci-common.h |  2 ++
 drivers/tty/serial/sh-sci.c        | 43 +++++++++++++++++++-----------
 3 files changed, 32 insertions(+), 15 deletions(-)

-- 
2.43.0