From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932516AbeAJFaX (ORCPT + 1 other); Wed, 10 Jan 2018 00:30:23 -0500 Received: from mail-it0-f45.google.com ([209.85.214.45]:36411 "EHLO mail-it0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932369AbeAJFaV (ORCPT ); Wed, 10 Jan 2018 00:30:21 -0500 X-Google-Smtp-Source: ACJfBouyBAY6tDUoDy+zY7FG6PDr200b6frF8jgr02WmXSw/vhHw9pdZgKh9z4fUkfXNIc8D/VWRuw== Subject: Re: [PATCH V2 1/5] usb: serial: f81534: add high baud rate support To: Johan Hovold Cc: gregkh@linuxfoundation.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, peter_hong@fintek.com.tw, "Ji-Ze Hong (Peter Hong)" References: <1515032961-29131-1-git-send-email-hpeter+linux_kernel@gmail.com> <20180109110841.GN11344@localhost> From: "Ji-Ze Hong (Peter Hong)" Message-ID: <18d4171a-1e1a-5476-dc9d-02a522cbf077@gmail.com> Date: Wed, 10 Jan 2018 13:30:18 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 MIME-Version: 1.0 In-Reply-To: <20180109110841.GN11344@localhost> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: Hi Johan, Johan Hovold 於 2018/1/9 下午 07:08 寫道: > On Thu, Jan 04, 2018 at 10:29:17AM +0800, Ji-Ze Hong (Peter Hong) wrote: >> The F81532/534 had 4 clocksource 1.846/18.46/14.77/24MHz and baud rates >> can be up to 1.5Mbits with 24MHz. >> >> This device may generate data overrun when baud rate setting to 921600bps >> or higher with old UART trigger level setting (8x14=112) with full >> loading. We'll change trigger level from 8x14=112 to 8x8=64 to avoid data >> overrun. >> >> Also the read/write of EP0 will be affected by this patch. The worst case >> of responding time is 20s when all serial port are full loading and trying >> to access EP0, so we change EP0 timeout from 10 to 20s. > > Surely you meant 1 and 2 seconds respectively here? And if you have > indeed measured response times close to 2000 ms then perhaps you want to > add even more margin? Normally, the communication with F81534 ep0 will take less than 1 sec (even only some milliseconds), but It maybe take much long time with huge loading with UART functional. We had tested it on BurnInTest, 4 ports with 921600bps + MSR status check to perform huge loading test. The worst case to read MSR register via ep0 will take 15~18 seconds. So We'll still remain the max waiting time for access ep0 with 2x10=20s in high baud rate mode. Thanks -- With Best Regards, Peter Hong