Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936083AbdCJMOG (ORCPT ); Fri, 10 Mar 2017 07:14:06 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:45104 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S936667AbdCJMN5 (ORCPT ); Fri, 10 Mar 2017 07:13:57 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Johan Hovold" , "Aidan Thornton" , "Grigori Goronzy" Date: Fri, 10 Mar 2017 11:46:23 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 198/370] USB: serial: ch341: reinitialize chip on reconfiguration In-Reply-To: X-SA-Exim-Connect-IP: 82.70.136.246 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3591 Lines: 112 3.16.42-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Aidan Thornton commit 4e46c410e050bcac36deadbd8e20449d078204e8 upstream. Changing the LCR register after initialization does not seem to be reliable on all chips (particularly not on CH341A). Restructure initialization and configuration to always reinit the chip on configuration changes instead and pass the LCR register value directly to the initialization command. (Note that baud rates above 500kbaud are incorrect, but they're incorrect in the same way both before and after this patch at least on the CH340G. Fixing this isn't a priority as higher baud rates don't seem that reliable anyway.) Cleaned-up version of a patch by Grigori Goronzy Signed-off-by: Aidan Thornton Reviewed-by: Grigori Goronzy Signed-off-by: Johan Hovold Signed-off-by: Ben Hutchings --- drivers/usb/serial/ch341.c | 37 ++++++++++++++++++++----------------- 1 file changed, 20 insertions(+), 17 deletions(-) --- a/drivers/usb/serial/ch341.c +++ b/drivers/usb/serial/ch341.c @@ -132,10 +132,10 @@ static int ch341_control_in(struct usb_d return r; } -static int ch341_set_baudrate(struct usb_device *dev, - struct ch341_private *priv) +static int ch341_init_set_baudrate(struct usb_device *dev, + struct ch341_private *priv, unsigned ctrl) { - short a, b; + short a; int r; unsigned long factor; short divisor; @@ -155,11 +155,10 @@ static int ch341_set_baudrate(struct usb factor = 0x10000 - factor; a = (factor & 0xff00) | divisor; - b = factor & 0xff; - r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x1312, a); - if (!r) - r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x0f2c, b); + /* 0x9c is "enable SFR_UART Control register and timer" */ + r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT, + 0x9c | (ctrl << 8), a | 0x80); return r; } @@ -218,10 +217,6 @@ static int ch341_configure(struct usb_de if (r < 0) goto out; - r = ch341_set_baudrate(dev, priv); - if (r < 0) - goto out; - /* expect two bytes 0x56 0x00 */ r = ch341_control_in(dev, CH341_REQ_READ_REG, 0x2518, 0, buffer, size); if (r < 0) @@ -236,11 +231,7 @@ static int ch341_configure(struct usb_de if (r < 0) goto out; - r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT, 0x501f, 0xd90a); - if (r < 0) - goto out; - - r = ch341_set_baudrate(dev, priv); + r = ch341_init_set_baudrate(dev, priv, 0); if (r < 0) goto out; @@ -355,16 +346,28 @@ static void ch341_set_termios(struct tty struct ch341_private *priv = usb_get_serial_port_data(port); unsigned baud_rate; unsigned long flags; + unsigned char ctrl; + int r; + + /* redundant changes may cause the chip to lose bytes */ + if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios)) + return; baud_rate = tty_get_baud_rate(tty); priv->baud_rate = baud_rate; + ctrl = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8; + if (baud_rate) { spin_lock_irqsave(&priv->lock, flags); priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS); spin_unlock_irqrestore(&priv->lock, flags); - ch341_set_baudrate(port->serial->dev, priv); + r = ch341_init_set_baudrate(port->serial->dev, priv, ctrl); + if (r < 0 && old_termios) { + priv->baud_rate = tty_termios_baud_rate(old_termios); + tty_termios_copy_hw(&tty->termios, old_termios); + } } else { spin_lock_irqsave(&priv->lock, flags); priv->line_control &= ~(CH341_BIT_DTR | CH341_BIT_RTS);