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[24.11.27.195]) by smtp.gmail.com with ESMTPSA id n64-v6sm1128000itc.32.2018.05.11.13.57.46 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 11 May 2018 13:57:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=wEzkG7XiPR6N4VSx5jf9hXc5flKbnEVBuOQkdXU//OE=; b=lmviZmDgVqfrwc+4/de3poG9El82EvhejjthRqM5SywM1ycnl/RSlvWmaFxkkWfCbs O1eBLjAoLJHrQQT4Qvir4Fsl6BKqCIYei5CzxZvOHp+HYePOdS5WTH1vdJMua4HDsYFp 90s2BaeQvBC3iwSF8ingtaB6ACkSAhWF+tDrAg15QkYKNHlIwQM/NaW0ibcTaS8Pv7I+ zDlEYJhIx9Mq0ryRFOtxYsuT682J71Bb+0wblEVIWdk1vuxbFghkmq2H08laL+S1Hwkr 82TSTvSPAimWVKIZ417otd16f6m6PFaDvClKh170KL+5dj33hUkzgTqSJ2CoW6Pzn9gR 3wdg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=wEzkG7XiPR6N4VSx5jf9hXc5flKbnEVBuOQkdXU//OE=; b=bUjKZpWaEzRCMzbG4ZHlEvbLWzd/Lm4EdrVspm42KkmJYe3NPKVOcfOTMQO4IoIoZe q/Bep2iWPVpcGNEURgD7el5PLcGqtqW2v2fb6avOmbPE+d+1nuQ/HnJ1g/L72ZqZhffV WOk2mQDqDxOBpSK7P1R/5lxIuTBZd0By1A7fKmupZHaxV529QLZ8HevvC2M+reQ73TDK AwJKktUvxfdusoDtivR9RG03qjfMMGJakx1tGP1L0IysEoJd3n+nEbZ52fvMsUbsA7RY 8lCvrDmFnY/WuR6+ptZuWH5H2kIahDyR8+ukmhWxDTor0v/W7SNoV9bYSJl6Gu/Ub8VL XM3g== X-Gm-Message-State: ALKqPwfUc+6q/S0hBZR+t6L6tIKTF0dLOUoEv9Z4JlwhcA2StBNKugJT ZVao9z5dJix5CRuaGy/OoDr/44SC X-Google-Smtp-Source: AB8JxZo5LN+So9HtBdzkSX5v215zy0xsPOJYOVGq+9P1LOHXoEc827vGJVb5H3Jo0laQhWkEl51/YQ== X-Received: by 2002:a6b:b889:: with SMTP id i131-v6mr7616755iof.300.1526072267413; Fri, 11 May 2018 13:57:47 -0700 (PDT) From: Calvin Lee To: qemu-devel@nongnu.org Date: Fri, 11 May 2018 14:57:23 -0600 Message-Id: <20180511205724.4039-2-cyrus296@gmail.com> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180511205724.4039-1-cyrus296@gmail.com> References: <20180511205724.4039-1-cyrus296@gmail.com> X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2607:f8b0:4001:c06::244 X-Mailman-Approved-At: Fri, 11 May 2018 18:28:34 -0400 Subject: [Qemu-devel] [PATCH RFC 1/2] PC Chipset: Improve serial divisor calculation X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Calvin Lee , pbonzini@redhat.com, dgilbert@redhat.com, mst@redhat.com Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) X-ZohoMail: RDKM_2 RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" This fixes several problems I found in the UART serial implementation. Now all divisor values are allowed, while before divisor values of zero and below the base baud rate were rejected. All changes are in reference to http://www.sci.muni.cz/docs/pc/serport.txt Signed-off-by: Calvin Lee --- I included a slight code-style change in this commit because it seemed close enough to the code I was editing to be relevant. If not, I can change the commit to not include this change. hw/char/serial.c | 23 +++++++++++++---------- 1 file changed, 13 insertions(+), 10 deletions(-) diff --git a/hw/char/serial.c b/hw/char/serial.c index 2c080c9862..4159a46a2f 100644 --- a/hw/char/serial.c +++ b/hw/char/serial.c @@ -150,13 +150,10 @@ static void serial_update_irq(SerialState *s) =20 static void serial_update_parameters(SerialState *s) { - int speed, parity, data_bits, stop_bits, frame_size; + float speed; + int parity, data_bits, stop_bits, frame_size; QEMUSerialSetParams ssp; =20 - if (s->divider =3D=3D 0 || s->divider > s->baudbase) { - return; - } - /* Start bit. */ frame_size =3D 1; if (s->lcr & 0x08) { @@ -169,14 +166,16 @@ static void serial_update_parameters(SerialState *s) } else { parity =3D 'N'; } - if (s->lcr & 0x04) + if (s->lcr & 0x04) { stop_bits =3D 2; - else + } else { stop_bits =3D 1; + } =20 data_bits =3D (s->lcr & 0x03) + 5; frame_size +=3D data_bits + stop_bits; - speed =3D s->baudbase / s->divider; + /* Zero divisor should give about 3500 baud */ + speed =3D (s->divider =3D=3D 0) ? 3500 : (float) s->baudbase / s->divi= der; ssp.speed =3D speed; ssp.parity =3D parity; ssp.data_bits =3D data_bits; @@ -184,7 +183,7 @@ static void serial_update_parameters(SerialState *s) s->char_transmit_time =3D (NANOSECONDS_PER_SECOND / speed) * frame_si= ze; qemu_chr_fe_ioctl(&s->chr, CHR_IOCTL_SERIAL_SET_PARAMS, &ssp); =20 - DPRINTF("speed=3D%d parity=3D%c data=3D%d stop=3D%d\n", + DPRINTF("speed=3D%.2f parity=3D%c data=3D%d stop=3D%d\n", speed, parity, data_bits, stop_bits); } =20 @@ -341,7 +340,11 @@ static void serial_ioport_write(void *opaque, hwaddr a= ddr, uint64_t val, default: case 0: if (s->lcr & UART_LCR_DLAB) { - s->divider =3D (s->divider & 0xff00) | val; + if (size =3D=3D 2) { + s->divider =3D (s->divider & 0xff00) | val; + } else if (size =3D=3D 4) { + s->divider =3D val; + } serial_update_parameters(s); } else { s->thr =3D (uint8_t) val; --=20 2.17.0