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Thu, 11 Sep 2025 09:06:57 -0700 (PDT) From: frank.chang@sifive.com To: qemu-devel@nongnu.org Cc: Alistair Francis , Palmer Dabbelt , =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= , Paolo Bonzini , qemu-riscv@nongnu.org (open list:SiFive Machines), Frank Chang Subject: [PATCH 2/4] hw/char: sifive_uart: Avoid pushing Tx FIFO when size is zero Date: Fri, 12 Sep 2025 00:06:44 +0800 Message-ID: <20250911160647.5710-3-frank.chang@sifive.com> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250911160647.5710-1-frank.chang@sifive.com> References: <20250911160647.5710-1-frank.chang@sifive.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=2607:f8b0:4864:20::52d; envelope-from=frank.chang@sifive.com; helo=mail-pg1-x52d.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 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, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action 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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @sifive.com) X-ZM-MESSAGEID: 1757606901843116600 Content-Type: text/plain; charset="utf-8" From: Frank Chang There's no need to call fifo8_push_all() when size is zero. Signed-off-by: Frank Chang Reviewed-by: Alistair Francis --- hw/char/sifive_uart.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/hw/char/sifive_uart.c b/hw/char/sifive_uart.c index 138c31fcabf..401f869680d 100644 --- a/hw/char/sifive_uart.c +++ b/hw/char/sifive_uart.c @@ -122,7 +122,9 @@ static void sifive_uart_write_tx_fifo(SiFiveUARTState *= s, const uint8_t *buf, qemu_log_mask(LOG_GUEST_ERROR, "sifive_uart: TX FIFO overflow"); } =20 - fifo8_push_all(&s->tx_fifo, buf, size); + if (size > 0) { + fifo8_push_all(&s->tx_fifo, buf, size); + } =20 if (fifo8_is_full(&s->tx_fifo)) { s->txfifo |=3D SIFIVE_UART_TXFIFO_FULL; --=20 2.49.0