From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 11 May 2001 20:29:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 11 May 2001 20:27:33 -0400 Received: from mailhost.nmt.edu ([129.138.4.52]:17937 "EHLO mailhost.nmt.edu") by vger.kernel.org with ESMTP id ; Fri, 11 May 2001 20:27:25 -0400 Date: Fri, 11 May 2001 18:27:23 -0600 From: Val Henson To: Theodore Tso Cc: linux-kernel@vger.kernel.org Subject: [PATCH] drivers/char/serial.c bug in ST16C654 detection Message-ID: <20010511182723.M18959@boardwalk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i Favorite-Color: Polka dot Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org This fixes a bug in the autoconfig_startech_uarts function in serial.c. The problem is that 0's are written to the baud rate registers in order to detect an XR16C850 or XR16C854. This makes the Exar ST16C654 go kablooey. Saving and restoring the baud rate registers after the test fixes it. I'm assuming that the XR16C85[04] detection works as is and doesn't need the original baud rate restored. If I'm wrong, I'll rewrite the patch. -VAL --- linux-2.4.5-pre1/drivers/char/serial.c Thu Apr 19 00:26:34 2001 +++ linux/drivers/char/serial.c Sat May 12 05:19:26 2001 @@ -3507,7 +3507,7 @@ struct serial_state *state, unsigned long flags) { - unsigned char scratch, scratch2, scratch3; + unsigned char scratch, scratch2, scratch3, scratch4; /* * First we check to see if it's an Oxford Semiconductor UART. @@ -3551,17 +3551,32 @@ * XR16C854. * */ + + /* Save the DLL and DLM */ + serial_outp(info, UART_LCR, UART_LCR_DLAB); + scratch3 = serial_inp(info, UART_DLL); + scratch4 = serial_inp(info, UART_DLM); + serial_outp(info, UART_DLL, 0); serial_outp(info, UART_DLM, 0); - state->revision = serial_inp(info, UART_DLL); + scratch2 = serial_inp(info, UART_DLL); scratch = serial_inp(info, UART_DLM); serial_outp(info, UART_LCR, 0); + if (scratch == 0x10 || scratch == 0x14) { + if (scratch == 0x10) + state->revision = scratch2; state->type = PORT_16850; return; } + /* Restore the DLL and DLM */ + + serial_outp(info, UART_LCR, UART_LCR_DLAB); + serial_outp(info, UART_DLL, scratch3); + serial_outp(info, UART_DLM, scratch4); + serial_outp(info, UART_LCR, 0); /* * We distinguish between the '654 and the '650 by counting * how many bytes are in the FIFO. I'm using this for now,