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authorGeert Uytterhoeven <geert+renesas@glider.be>2018-09-05 15:11:25 +0200
committerPaolo Bonzini <pbonzini@redhat.com>2018-10-02 18:47:55 +0200
commit71bb4ce1b5592cdc03abc48cdf4ecb15b2db81a0 (patch)
tree30282f8a2238c83d1bdfe7335c9323003b50816f /util
parente811da7fe229cc17d98b230bdfeaf6d0631ea987 (diff)
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hw/char/sh_serial: Add timeout handling to unbreak serial input
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 <rob@landley.net> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Tested-by: Ulrich Hecht <uli@fpond.eu> Tested-by: Rob Landley <rob@landley.net> Tested-by: Rich Felker <dalias@libc.org> Message-Id: <20180905131125.12635-1-geert+renesas@glider.be> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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