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Re: [Qemu-devel] [PATCH qemu v2] hw/char/sh_serial: Add timeout handling

From: Geert Uytterhoeven
Subject: Re: [Qemu-devel] [PATCH qemu v2] hw/char/sh_serial: Add timeout handling to unbreak serial input
Date: Fri, 28 Sep 2018 14:36:36 +0200

Hi Paolo,

On Tue, Sep 11, 2018 at 3:11 PM Paolo Bonzini <address@hidden> wrote:
> On 05/09/2018 15:11, Geert Uytterhoeven 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 aforementioned 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 interactive console.
> >
> > Reported-by: Rob Landley <address@hidden>
> > Signed-off-by: Geert Uytterhoeven <address@hidden>
> > Tested-by: Ulrich Hecht <address@hidden>
> > Tested-by: Rob Landley <address@hidden>
> > Tested-by: Rich Felker <address@hidden>

> Queued, thanks.

Does that mean it should show up in qemu.git anytime soon?

Thanks, and have a nice weekend!



Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- address@hidden

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

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