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[2a01:cb08:19b:ba00:4d97:cdf5:dfbb:a74f]) by smtp.gmail.com with ESMTPSA id m20sm19183537wmq.11.2021.11.28.04.07.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 28 Nov 2021 04:07:45 -0800 (PST) From: =?utf-8?q?Olivier_H=C3=A9riveaux?= To: qemu-devel@nongnu.org Cc: qemu-trivial@nongnu.org, alistair@alistair23.me, peter.maydell@linaro.org, =?utf-8?q?Olivier_H=C3=A9riveaux?= Subject: [PATCH] Fix STM32F2XX USART data register readout Date: Sun, 28 Nov 2021 13:07:23 +0100 Message-Id: <20211128120723.4053-1-olivier.heriveaux@ledger.fr> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 X-Host-Lookup-Failed: Reverse DNS lookup failed for 2a00:1450:4864:20::32b (failed) Received-SPF: permerror client-ip=2a00:1450:4864:20::32b; envelope-from=olivier.heriveaux@ledger.fr; helo=mail-wm1-x32b.google.com X-Spam_score_int: -12 X-Spam_score: -1.3 X-Spam_bar: - X-Spam_report: (-1.3 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, PDS_HP_HELO_NORDNS=0.001, RCVD_IN_DNSWL_NONE=-0.0001, RDNS_NONE=0.793, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-Mailman-Approved-At: Sun, 28 Nov 2021 09:45:39 -0500 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Fix issue where the data register may be overwritten by next character reception before being read and returned. Signed-off-by: Olivier Hériveaux Reviewed-by: Peter Maydell Reviewed-by: Alistair Francis --- hw/char/stm32f2xx_usart.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/hw/char/stm32f2xx_usart.c b/hw/char/stm32f2xx_usart.c index 8df0832424..fde67f4f03 100644 --- a/hw/char/stm32f2xx_usart.c +++ b/hw/char/stm32f2xx_usart.c @@ -103,10 +103,11 @@ static uint64_t stm32f2xx_usart_read(void *opaque, hwaddr addr, return retvalue; case USART_DR: DB_PRINT("Value: 0x%" PRIx32 ", %c\n", s->usart_dr, (char) s->usart_dr); + retvalue = s->usart_dr & 0x3FF; s->usart_sr &= ~USART_SR_RXNE; qemu_chr_fe_accept_input(&s->chr); qemu_set_irq(s->irq, 0); - return s->usart_dr & 0x3FF; + return retvalue; case USART_BRR: return s->usart_brr; case USART_CR1: