> On July 30, 2018 at 3:02 PM Geert Uytterhoeven <geert+renesas@xxxxxxxxx> wrote:
>
>
> As of commit 18e8cf159177100e ("serial: sh-sci: increase RX FIFO trigger
> defaults for (H)SCIF") in Linux v4.11-rc1, the serial console on the
> QEMU SH4 target is broken: it delays serial input until enough data has
> been received.
>
> Since aformentioned commit, the Linux SCIF driver programs the Receive
> FIFO Data Count Trigger bits in the FIFO Control Register, to postpone
> generating a receive interrupt until:
> 1. At least the receive trigger count of bytes of data are available
> in the receive FIFO, OR
> 2. No further data has been received for at least 15 etu after the
> last received data.
>
> While QEMU implements the former, it does not implement the latter.
> Hence the receive interrupt is not generated until the former condition
> is met.
>
> Fix this by adding basic timeout handling. As the QEMU SCIF emulation
> ignores any serial speed programming, the timeout value used conforms to
> a default speed of 9600 bps, which is fine for any interative console.
>
> Reported-by: Rob Landley <rob@xxxxxxxxxxx>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Works for me, kernel 4.18-rc7 for rts7751r2dplus.
Tested-by: Ulrich Hecht <uli@xxxxxxxx>
CU
Uli
