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[98.223.182.45]) by smtp.gmail.com with ESMTPSA id y1sm1984027ioj.32.2021.01.27.19.36.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 Jan 2021 19:36:57 -0800 (PST) From: Iris Johnson To: Iris Johnson Subject: [PATCH] hw/char/exynos4210_uart: Fix buffer size reporting with FIFO disabled Date: Thu, 28 Jan 2021 03:36:55 +0000 Message-Id: <20210128033655.1029577-1-iris@modwiz.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Received-SPF: none client-ip=2607:f8b0:4864:20::12b; envelope-from=iris@modwiz.com; helo=mail-il1-x12b.google.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_NONE=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Igor Mitsyanko , "open list:All patches CC here" , "open list:Exynos" , =?utf-8?q?Marc-Andr=C3=A9_Lureau?= , Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" 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 --- hw/char/exynos4210_uart.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/hw/char/exynos4210_uart.c b/hw/char/exynos4210_uart.c index 6361df2ad3..9b21d201b3 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)