From 40b4c2ae90e4f864a1015ff748a4af00518ff0c0 Mon Sep 17 00:00:00 2001 From: Iris Johnson Date: Thu, 28 Jan 2021 03:36:55 +0000 Subject: hw/char/exynos4210_uart: Fix buffer size reporting with FIFO disabled Currently the Exynos 4210 UART code always reports available FIFO space when the backend checks for buffer space. When the FIFO is disabled this is behavior causes the backend chardev code to replace the data before the guest can read it. This patch changes adds the logic to report the capacity properly when the FIFO is not being used. Buglink: https://bugs.launchpad.net/qemu/+bug/1913344 Signed-off-by: Iris Johnson Message-id: 20210128033655.1029577-1-iris@modwiz.com Reviewed-by: Peter Maydell Signed-off-by: Peter Maydell --- hw/char/exynos4210_uart.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'hw/char/exynos4210_uart.c') diff --git a/hw/char/exynos4210_uart.c b/hw/char/exynos4210_uart.c index 6361df2..9b21d20 100644 --- a/hw/char/exynos4210_uart.c +++ b/hw/char/exynos4210_uart.c @@ -553,7 +553,11 @@ static int exynos4210_uart_can_receive(void *opaque) { Exynos4210UartState *s = (Exynos4210UartState *)opaque; - return fifo_empty_elements_number(&s->rx); + if (s->reg[I_(UFCON)] & UFCON_FIFO_ENABLE) { + return fifo_empty_elements_number(&s->rx); + } else { + return !(s->reg[I_(UTRSTAT)] & UTRSTAT_Rx_BUFFER_DATA_READY); + } } static void exynos4210_uart_receive(void *opaque, const uint8_t *buf, int size) -- cgit v1.1