Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030217AbVIIKSk (ORCPT ); Fri, 9 Sep 2005 06:18:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030220AbVIIKSk (ORCPT ); Fri, 9 Sep 2005 06:18:40 -0400 Received: from caramon.arm.linux.org.uk ([212.18.232.186]:20499 "EHLO caramon.arm.linux.org.uk") by vger.kernel.org with ESMTP id S1030217AbVIIKSj (ORCPT ); Fri, 9 Sep 2005 06:18:39 -0400 Date: Fri, 9 Sep 2005 11:18:35 +0100 From: Russell King To: Mathias Adam Cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH] 8250.c: Fix to make 16C950 UARTs work Message-ID: <20050909111835.D17575@flint.arm.linux.org.uk> Mail-Followup-To: Mathias Adam , linux-kernel@vger.kernel.org References: <20050909013144.GA6660@adamis.de> <4320EC45.1080108@stesmi.com> <20050909024926.GA13643@adamis.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <20050909024926.GA13643@adamis.de>; from a2@adamis.de on Fri, Sep 09, 2005 at 04:49:27AM +0200 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2084 Lines: 60 A couple of comments - see below. On Fri, Sep 09, 2005 at 04:49:27AM +0200, Mathias Adam wrote: > --- linux-2.6.13-org/drivers/serial/8250.c 2005-08-29 01:41:01.000000000 +0200 > +++ linux-2.6.13/drivers/serial/8250.c 2005-09-09 02:16:49.000000000 +0200 > @@ -1665,7 +1665,7 @@ > struct uart_8250_port *up = (struct uart_8250_port *)port; > unsigned char cval, fcr = 0; > unsigned long flags; > - unsigned int baud, quot; > + unsigned int baud, quot, max_baud; > > switch (termios->c_cflag & CSIZE) { > case CS5: > @@ -1697,9 +1697,28 @@ > /* > * Ask the core to calculate the divisor for us. > */ > - baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16); > + max_baud = (up->port.type == PORT_16C950 ? port->uartclk/4 : port->uartclk/16); > + baud = uart_get_baud_rate(port, termios, old, 0, max_baud); > quot = serial8250_get_divisor(port, baud); > > + /* > + * 16C950 supports additional prescaler ratios between 1:16 and 1:4 > + * thus increasing max baud rate to uartclk/4. The following was taken > + * from kernel 2.4 by Mathias Adam to make the Socket > + * Bluetooth CF Card work under 2.6.13. > + */ > + if (up->port.type == PORT_16C950) { > + unsigned int baud_base = port->uartclk/16; baud_base appears unused. > + if (baud <= port->uartclk/16) > + serial_icr_write(up, UART_TCR, 0); > + else if (baud <= port->uartclk/8) { > + serial_icr_write(up, UART_TCR, 0x8); > + } else if (baud <= port->uartclk/4) { > + serial_icr_write(up, UART_TCR, 0x4); > + } else > + serial_icr_write(up, UART_TCR, 0); baud can't be larger than port->uartclk/4 since you limited it above. > + } > + > /* > * Oxford Semi 952 rev B workaround > */ -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 Serial core - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/