From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 19A93C433E0 for ; Mon, 18 Jan 2021 12:44:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D84872253A for ; Mon, 18 Jan 2021 12:44:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404270AbhARMoB (ORCPT ); Mon, 18 Jan 2021 07:44:01 -0500 Received: from mail.kernel.org ([198.145.29.99]:53374 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404258AbhARMnn (ORCPT ); Mon, 18 Jan 2021 07:43:43 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id E68D4224B8; Mon, 18 Jan 2021 12:43:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1610973782; bh=cnYltJ7zUV+fZqR6uHbvvuu1Kt2sdtSKH8lV9MldO9M=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Pe0tZDZ9HpTSaSWYPslmezr5rJkdmANyDW5cK8qWRMpSBoJz6YTJ7tmS4rAmRZvLd j6g8Ne5APyTRlaviyNw5EtoMvam3T9sosOErFLhbVncpMub43A11wxHJRR8sond29C RWhlpbW80zGhPhlXEJRiouHXKa0AicosLvH/1g+8= Date: Mon, 18 Jan 2021 13:42:59 +0100 From: Greg Kroah-Hartman To: Johan Hovold Cc: linux-usb@vger.kernel.org, Sheng Long Wang , Wang Sheng Long Subject: Re: [PATCH 1/6] USB: serial: cp210x: add support for software flow control Message-ID: References: <20210118111331.5048-1-johan@kernel.org> <20210118111331.5048-2-johan@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210118111331.5048-2-johan@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Mon, Jan 18, 2021 at 12:13:26PM +0100, Johan Hovold wrote: > From: Wang Sheng Long > > When data is transmitted between two serial ports, the phenomenon of > data loss often occurs. The two kinds of flow control commonly used in > serial communication are hardware flow control and software flow > control. > > In serial communication, If you only use RX/TX/GND Pins, you can't do > hardware flow. So we often used software flow control and prevent data > loss. The user sets the software flow control through the application > program, and the application program sets the software flow control mode > for the serial port chip through the driver. > > For the cp210 serial port chip, its driver lacks the software flow > control setting code, so the user cannot set the software flow control > function through the application program. This adds the missing software > flow control. > > Signed-off-by: Wang Sheng Long > Link: https://lore.kernel.org/r/20210104094502.3942-1-china_shenglong@163.com > [ johan: rework properly on top of recent termios changes ] > Signed-off-by: Johan Hovold > --- > drivers/usb/serial/cp210x.c | 67 +++++++++++++++++++++++++++++++++++-- > 1 file changed, 65 insertions(+), 2 deletions(-) > > diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c > index fbb10dfc56e3..5bd14770065b 100644 > --- a/drivers/usb/serial/cp210x.c > +++ b/drivers/usb/serial/cp210x.c > @@ -377,6 +377,16 @@ static struct usb_serial_driver * const serial_drivers[] = { > #define CONTROL_WRITE_DTR 0x0100 > #define CONTROL_WRITE_RTS 0x0200 > > +/* CP210X_(GET|SET)_CHARS */ > +struct cp210x_special_chars { > + u8 bEofChar; > + u8 bErrorChar; > + u8 bBreakChar; > + u8 bEventChar; > + u8 bXonChar; > + u8 bXoffChar; > +}; > + > /* CP210X_VENDOR_SPECIFIC values */ > #define CP210X_READ_2NCONFIG 0x000E > #define CP210X_READ_LATCH 0x00C2 > @@ -1074,11 +1084,38 @@ static void cp210x_disable_event_mode(struct usb_serial_port *port) > port_priv->event_mode = false; > } > > +static int cp210x_set_chars(struct usb_serial_port *port, > + struct cp210x_special_chars *chars) > +{ > + struct cp210x_port_private *port_priv = usb_get_serial_port_data(port); > + struct usb_serial *serial = port->serial; > + void *dmabuf; > + int result; > + > + dmabuf = kmemdup(chars, sizeof(*chars), GFP_KERNEL); > + if (!dmabuf) > + return -ENOMEM; > + > + result = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0), > + CP210X_SET_CHARS, REQTYPE_HOST_TO_INTERFACE, 0, > + port_priv->bInterfaceNumber, > + dmabuf, sizeof(*chars), USB_CTRL_SET_TIMEOUT); > + > + kfree(dmabuf); > + > + if (result < 0) { > + dev_err(&port->dev, "failed to set special chars: %d\n", result); > + return result; > + } This is an "open coded" usb_control_msg_send() call :) Other than that minor thing: Reviewed-by: Greg Kroah-Hartman