From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754027AbbJPLUB (ORCPT ); Fri, 16 Oct 2015 07:20:01 -0400 Received: from mail-lf0-f48.google.com ([209.85.215.48]:35312 "EHLO mail-lf0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753526AbbJPLT7 (ORCPT ); Fri, 16 Oct 2015 07:19:59 -0400 Subject: Re: [PATCH] USB: serial: cp210x: Adding tx_empty() to avoid cp2108 failure To: Konstantin Shkolnyy , johan@kernel.org References: <1444946828-18182-1-git-send-email-konstantin.shkolnyy@gmail.com> Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org From: Sergei Shtylyov Message-ID: <5620DD5D.9080602@cogentembedded.com> Date: Fri, 16 Oct 2015 14:19:57 +0300 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <1444946828-18182-1-git-send-email-konstantin.shkolnyy@gmail.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello. On 10/16/2015 1:07 AM, Konstantin Shkolnyy wrote: > Occasionally, writing data and immediately closing the port makes cp2108 > stop responding. The device had to be unplugged to clear the error. > The failure is induced by shutting down the device while its Tx queue still has > unsent data. Reporting the correct amount of those data avoids the problem. > Adding tx_empty() has no adverse effect on other cp210x devices. > > Signed-off-by: Konstantin Shkolnyy > --- > drivers/usb/serial/cp210x.c | 30 ++++++++++++++++++++++++++++++ > 1 file changed, 30 insertions(+) > > diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c > index eac7cca..0189e64 100644 > --- a/drivers/usb/serial/cp210x.c > +++ b/drivers/usb/serial/cp210x.c [...] > @@ -249,6 +251,16 @@ static struct usb_serial_driver * const serial_drivers[] = { > #define CP210X_GET_CHARS 0x0E > #define CP210X_GET_PROPS 0x0F > #define CP210X_GET_COMM_STATUS 0x10 > +/* Data returned by CP210X_GET_COMM_STATUS -- h/w doc says it's 0x13 bytes */ > +struct cp210x_comm_status { > + u32 errors; > + u32 hold_reasons; > + u32 amount_in_in_queue; > + u32 amount_in_out_queue; > + u8 eof_received; > + u8 wait_for_immediate; > + u8 reserved; > +}; Please don't declare structures amidst of the command #define's. > #define CP210X_RESET 0x11 > #define CP210X_PURGE 0x12 > #define CP210X_SET_FLOW 0x13 > @@ -479,6 +491,24 @@ static void cp210x_close(struct usb_serial_port *port) > cp210x_set_config_single(port, CP210X_IFC_ENABLE, UART_DISABLE); > } > > +static bool cp210x_tx_empty(struct usb_serial_port *port) > +{ > + int err; > + Empty line hardly needed here. > + /* get_config needs "array of integers large enough", so pad to 0x14 bytes */ > + struct cp210x_comm_status_container { > + struct cp210x_comm_status sts; /* 0x13 bytes */ > + u8 pad_to_0x14_bytes; > + } comm_sts_cont; > + > + err = cp210x_get_config(port, CP210X_GET_COMM_STATUS, (unsigned int *) &comm_sts_cont, 0x13); > + Empty line hardly needed here. > + if (!err) > + if (comm_sts_cont.sts.amount_in_out_queue) Why not collapse these two *if* statements into one? > + return false; > + return true; > +} > + [...] MBR, Sergei