Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755587AbaJ1Xca (ORCPT ); Tue, 28 Oct 2014 19:32:30 -0400 Received: from jim.sh ([75.150.123.25]:49630 "EHLO psychosis.jim.sh" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754795AbaJ1XcZ (ORCPT ); Tue, 28 Oct 2014 19:32:25 -0400 X-Greylist: delayed 317 seconds by postgrey-1.27 at vger.kernel.org; Tue, 28 Oct 2014 19:32:25 EDT Date: Tue, 28 Oct 2014 19:26:57 -0400 From: Jim Paris To: Oliver Neukum , Greg Kroah-Hartman , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] cdc-acm: ensure that termios get set when the port is opened Message-ID: <20141028232649.GA1064@psychosis.jim.sh> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Do what other drivers like ftdi_sio do, and ensure that termios are written to the device when the port is first opened. Signed-off-by: Jim Paris --- Tested on v3.16.5. I've seen a problem on two CDC-ACM systems based on a Segger J-Link where the port does not get initialized at the correct baudrate when opening (using e.g. python-serial). I think this occurs when the tty device was previously opened at the same baudrate, then the device was unplugged and replugged. While the port is open, manually switching to a different baudrate and back fixes it. Debug output in the failing case is e.g.: Oct 28 18:37:45 pilot kernel: [1214446.586460] tty ttyACM0: acm_tty_install Oct 28 18:37:45 pilot kernel: [1214446.586474] tty ttyACM0: acm_tty_open Oct 28 18:37:45 pilot kernel: [1214446.586477] cdc_acm 1-2.7:1.0: acm_port_activate Oct 28 18:37:45 pilot kernel: [1214446.586670] cdc_acm 1-2.7:1.0: acm_ctrl_msg - rq 0x22, val 0x3, len 0x0, result 0 which is missing the important: Oct 28 19:03:18 pilot kernel: [1215981.178020] cdc_acm 1-2.7:1.0: acm_tty_set_termios - set line: 38400 0 0 8 Oct 28 19:03:18 pilot kernel: [1215981.178135] cdc_acm 1-2.7:1.0: acm_ctrl_msg - rq 0x20, val 0x0, len 0x7, result 7 that I get when changing settings to something different than they previously were. I don't really follow all of the termios and tty stuff, so I don't know if this is the right fix or the real cause. I suspect it have to do with cached values associated with the particular TTY ("lazy saved data" in tty-io.c); this patch just does what I see in ftdi_sio and ensures that the termios settings are written to the device when the port is opened. --- drivers/usb/class/cdc-acm.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index e934e19f49f5..144bf43c9190 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -495,15 +495,6 @@ error_init_termios: return retval; } -static int acm_tty_open(struct tty_struct *tty, struct file *filp) -{ - struct acm *acm = tty->driver_data; - - dev_dbg(tty->dev, "%s\n", __func__); - - return tty_port_open(&acm->port, tty, filp); -} - static void acm_port_dtr_rts(struct tty_port *port, int raise) { struct acm *acm = container_of(port, struct acm, port); @@ -1000,6 +991,18 @@ static void acm_tty_set_termios(struct tty_struct *tty, } } +static int acm_tty_open(struct tty_struct *tty, struct file *filp) +{ + struct acm *acm = tty->driver_data; + + dev_dbg(tty->dev, "%s\n", __func__); + + if (tty) + acm_tty_set_termios(tty, NULL); + + return tty_port_open(&acm->port, tty, filp); +} + static const struct tty_port_operations acm_port_ops = { .dtr_rts = acm_port_dtr_rts, .shutdown = acm_port_shutdown, -- 2.1.0 -- 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/