* [PATCH] hw/char/exynos4210_uart: Fix missing call to report ready for input
@ 2021-01-30 18:40 Iris Johnson
2021-02-02 11:07 ` Peter Maydell
0 siblings, 1 reply; 2+ messages in thread
From: Iris Johnson @ 2021-01-30 18:40 UTC (permalink / raw)
Cc: Peter Maydell, Iris Johnson, Igor Mitsyanko,
open list:All patches CC here, open list:Exynos,
Marc-André Lureau, Paolo Bonzini
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>
---
hw/char/exynos4210_uart.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/hw/char/exynos4210_uart.c b/hw/char/exynos4210_uart.c
index 6361df2ad3..51ba862d0b 100644
--- a/hw/char/exynos4210_uart.c
+++ b/hw/char/exynos4210_uart.c
@@ -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);
--
2.25.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] hw/char/exynos4210_uart: Fix missing call to report ready for input
2021-01-30 18:40 [PATCH] hw/char/exynos4210_uart: Fix missing call to report ready for input Iris Johnson
@ 2021-02-02 11:07 ` Peter Maydell
0 siblings, 0 replies; 2+ messages in thread
From: Peter Maydell @ 2021-02-02 11:07 UTC (permalink / raw)
To: Iris Johnson
Cc: Igor Mitsyanko, Marc-André Lureau, open list:Exynos,
open list:All patches CC here, Paolo Bonzini
On Sat, 30 Jan 2021 at 18:42, Iris Johnson <iris@modwiz.com> wrote:
>
> 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>
> ---
> hw/char/exynos4210_uart.c | 1 +
Applied to target-arm.next, thanks.
-- PMM
^ permalink raw reply [flat|nested] 2+ messages in thread
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2021-01-30 18:40 [PATCH] hw/char/exynos4210_uart: Fix missing call to report ready for input Iris Johnson
2021-02-02 11:07 ` Peter Maydell
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