From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Subject: Re: [PATCH] tty: serial: 8250_mtk: Fix quot calculation Date: Wed, 5 Nov 2014 19:27:20 -0800 Message-ID: <20141106032720.GA10803@kroah.com> References: <1412871811-5986-1-git-send-email-matthias.bgg@gmail.com> <20141009215228.GA23507@kroah.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Matthias Brugger Cc: "linux-kernel@vger.kernel.org" , jslaby@suse.cz, Heiko =?iso-8859-1?Q?St=FCbner?= , Yingjoe Chen , Howard Chen , linux-serial@vger.kernel.org List-Id: linux-serial@vger.kernel.org On Fri, Oct 10, 2014 at 10:10:45AM +0200, Matthias Brugger wrote: > 2014-10-09 23:52 GMT+02:00 Greg KH : > > On Thu, Oct 09, 2014 at 06:23:31PM +0200, Matthias Brugger wrote: > >> The calculation of value quot for highspeed register set to three > >> was wrong. This patch fixes the calculation so that the serial port > >> for baudrates bigger then 576000 baud is working correctly. > >> > >> Signed-off-by: Matthias Brugger > >> --- > >> drivers/tty/serial/8250/8250_mtk.c | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c > >> index 1c4b4bf..4376c48 100644 > >> --- a/drivers/tty/serial/8250/8250_mtk.c > >> +++ b/drivers/tty/serial/8250/8250_mtk.c > >> @@ -81,7 +81,7 @@ mtk8250_set_termios(struct uart_port *port, struct ktermios *termios, > >> /* Set to highest baudrate supported */ > >> if (baud >= 1152000) > >> baud = 921600; > >> - quot = DIV_ROUND_CLOSEST(port->uartclk, 256 * baud); > >> + quot = (port->uartclk / (256 * baud)) + 1; > >> } > >> > >> /* > > > > Has this always been incorrect, or was it caused by a specific patch? > > It has always been incorrect :o > > > Should it go to the stable kernels? If so, how far back? > > No need to go to the stable kernels. The driver is only in linux-next. Well, it's in 3.18-rc1, so it should at least go into 3.18-final. I'll queue it up for that. thanks, greg k-h