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hw/char/exynos4210_uart: Fix missing call to report ready for input

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When the frontend device has no space for a read the fd is removed
from polling to allow time for the guest to read and clear the buffer.
Without the call to qemu_chr_fe_accept_input(), the poll will not be
broken out of when the guest has cleared the buffer causing significant
IO delays that get worse with smaller buffers.

Buglink: https://bugs.launchpad.net/qemu/+bug/1913341
Signed-off-by: Iris Johnson <iris@modwiz.com>
Message-id: 20210130184016.1787097-1-iris@modwiz.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Iris Johnson 2021-01-30 18:40:17 +00:00 committed by Peter Maydell
parent 40b4c2ae90
commit f2c0fb93a4
1 changed files with 1 additions and 0 deletions
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hw/char/exynos4210_uart.c
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@ -519,6 +519,7 @@ static uint64_t exynos4210_uart_read(void *opaque, hwaddr offset,
s->reg[I_(UTRSTAT)] &= ~UTRSTAT_Rx_BUFFER_DATA_READY;
res = s->reg[I_(URXH)];
}
qemu_chr_fe_accept_input(&s->chr);
exynos4210_uart_update_dmabusy(s);
trace_exynos_uart_read(s->channel, offset,
exynos4210_uart_regname(offset), res);