From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E8788CA101F for ; Mon, 15 Sep 2025 03:48:35 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uy0Bf-00055n-RV; Sun, 14 Sep 2025 23:47:32 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uy0Be-00055H-EF for qemu-devel@nongnu.org; Sun, 14 Sep 2025 23:47:30 -0400 Received: from mail-ej1-x631.google.com ([2a00:1450:4864:20::631]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1uy0BW-0000zS-6M for qemu-devel@nongnu.org; Sun, 14 Sep 2025 23:47:29 -0400 Received: by mail-ej1-x631.google.com with SMTP id a640c23a62f3a-b07e3a77b72so226401066b.0 for ; Sun, 14 Sep 2025 20:47:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1757908037; x=1758512837; darn=nongnu.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=BLBfSRubhbN9WyMaOuxIZltAuqluOkaeA1nF2WlSRgs=; b=WutWXstKmp0wn1whp/l3abK5637aTy++4atAjpWEoueyKsDTxDStn9gBo+IMzxmQTy gSOrFvCv1IH47QSRQCJbe3OzvKcq+G9UQp10aghcpjE17fAOQRsrydlC35RDvmqTUw3J 5VD1LFNPe8AMsfgk8WryUpLjiqAsSK2pAOOyUlJordUlmmVYZrdW/Nx1OCQrnS6RNDXW 3UY74LBjw44hXdahIGZElLEjrcR0GgJY7sR3G3ZEHhXJZEXTAUH4drfycnhqhqZ8ZGHd mIQDldoaLXSO1+5f8L64y9zzXq2P0MgjrZPbzoJLyNmbSL0cixyz7f3DaqFAxEydq5hJ TTFg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1757908037; x=1758512837; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=BLBfSRubhbN9WyMaOuxIZltAuqluOkaeA1nF2WlSRgs=; b=wAT714WtVB/bpPv5iST0iiwav/mGV/f0w7e1sgdc9bqeXYlbGjB/M2T1UvB5WELJPC 8gYK42DV1tPhaXX/fC+4pxk95fi2aVav41FwORC1EK+VV1ZJMq3lM9+n2Ov9Xbyolf+5 QnuNf4F9sBsTF2xUXBsufXC4mLbWFmJ33MAFcE9tKD5bvaAei1LvfJ7NNZ8+1we2MySa +WpFHuojTz2yOB2IAG8bZT3y+1lnPkD+K3bRTCbr4E8rZgGDKzTFnXwAFHzdLVKFEXVB RgXkDTe9DOegdG4jfl14i8NhwZiAEIdsfj3Dw9zs2i3JRGpzNlQCtvnSXPl4j9JlsVie TD2g== X-Gm-Message-State: AOJu0YwNnpE4Xlaun/wSBi1N8QL2IVeQ6a53aI4CtUDerYBvPEQ0ySDW L7V1/3BZDodIa5akXFXlhE8xmRmBT7yp4iJ1AxCjNeBvP2Z17cNDooqoDNJpz96TJUyQ5ggQwUT 1NPsKL61AJayxmCVIYg7iHcsobhLVKuo= X-Gm-Gg: ASbGnctjCwWXvWcreQQIUCD+wZ/UpYlPrg+nZhu32e9GvRnECXkg+cKTilMV8qt+dY2 IL7Cy38NM0b0qjJ935ztuy3A2CnpYvgzi7royp+KS3NepJBUgwOvglkAXrriNFnAlxPmtbgZWd0 0DdYvCRf+4GMNL41kqrOyASZ6D5m+S134AP1CIvoUnuniuMGbaM1b+lZK2YtuebfLv3A14yEcsW 4ZYE1SifIEpLzBbjQnzufDe2GF4SQPRUD2wOdKeUCZdkqu8 X-Google-Smtp-Source: AGHT+IHj3v0ZniuKqqBSRXpL6LlMwMSi7G+4ORYZqYS445OqjuZBOhEWMuFU2TJfMGLD2Mxg+n92u8K9EkUzX8r70/Y= X-Received: by 2002:a17:906:9f8c:b0:b0e:d477:4978 with SMTP id a640c23a62f3a-b0ed47773f7mr287904066b.32.1757908036817; Sun, 14 Sep 2025 20:47:16 -0700 (PDT) MIME-Version: 1.0 References: <20250911160647.5710-1-frank.chang@sifive.com> <20250911160647.5710-3-frank.chang@sifive.com> In-Reply-To: <20250911160647.5710-3-frank.chang@sifive.com> From: Alistair Francis Date: Mon, 15 Sep 2025 13:46:49 +1000 X-Gm-Features: Ac12FXyfTDmXLzDrqQSLIUSySrfc2rXrqG3-E-lp1NFRMpmb1YLMYUkQ8FzoOXk Message-ID: Subject: Re: [PATCH 2/4] hw/char: sifive_uart: Avoid pushing Tx FIFO when size is zero To: frank.chang@sifive.com Cc: qemu-devel@nongnu.org, Alistair Francis , Palmer Dabbelt , =?UTF-8?B?TWFyYy1BbmRyw6kgTHVyZWF1?= , Paolo Bonzini , "open list:SiFive Machines" Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=2a00:1450:4864:20::631; envelope-from=alistair23@gmail.com; helo=mail-ej1-x631.google.com X-Spam_score_int: -17 X-Spam_score: -1.8 X-Spam_bar: - X-Spam_report: (-1.8 / 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, FREEMAIL_ENVFROM_END_DIGIT=0.25, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham 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+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Fri, Sep 12, 2025 at 2:08=E2=80=AFAM wrote: > > 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 Alistair > --- > 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"); > } > > - fifo8_push_all(&s->tx_fifo, buf, size); > + if (size > 0) { > + fifo8_push_all(&s->tx_fifo, buf, size); > + } > > if (fifo8_is_full(&s->tx_fifo)) { > s->txfifo |=3D SIFIVE_UART_TXFIFO_FULL; > -- > 2.49.0 > >