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=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 35BE0C4320A for ; Sat, 7 Aug 2021 14:56:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1373960EE1 for ; Sat, 7 Aug 2021 14:56:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230422AbhHGO4b (ORCPT ); Sat, 7 Aug 2021 10:56:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42182 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229503AbhHGO43 (ORCPT ); Sat, 7 Aug 2021 10:56:29 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C188CC0613CF; Sat, 7 Aug 2021 07:56:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Content-Transfer-Encoding:Content-Type :In-Reply-To:MIME-Version:Date:Message-ID:From:References:Cc:To:Subject: Sender:Reply-To:Content-ID:Content-Description; bh=NMz/26uT2WRA5zyrDgg3yIeUQzzboyU0k+N1bjM2MZM=; b=cPZ15ULomfdRX2fu5rlpG0qu3i mRzqYnOPSL2JH4cHh9uaamsjMfXT1UeA4ANq+FkpgMcIirnS7YSyeYNYFgRDPuNYK/IUF52QJBHCK p/R7CNivssfZmXD86NPwuy/akez7R0VsvuhfOnF03M6pGW6ITu5q+U/0D56XvKaxx1m0oW0Lynd+W FXuAUP/DKhd9B/5G8kUfovTTZYpIXpUdYoOfk4X/gs/EzMH20wmvmH8S2C1n5GluP/UsIyve5uFZr mT8TVBgHAUiiLJEFrhSXCmqfrDDF5OUrdS4DmHDFpJRYz3Hpgsgkv9nKEtvicllVbrr/bx7som5wJ cmPm4yPA==; Received: from [2601:1c0:6280:3f0::aa0b] by desiato.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mCNj4-006i7G-GC; Sat, 07 Aug 2021 14:55:31 +0000 Subject: Re: Embedded USB Debug(EUD) driver To: Subhashini Rao Beerisetty , Greg KH Cc: linux-usb@vger.kernel.org, kernelnewbies , LKML References: From: Randy Dunlap Message-ID: <1cd59c72-2221-ec3a-da8d-ca377530db80@infradead.org> Date: Sat, 7 Aug 2021 07:54:57 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/7/21 7:23 AM, Subhashini Rao Beerisetty wrote: > On Sat, Jul 31, 2021 at 11:12 AM Greg KH wrote: >> >> On Fri, Jul 30, 2021 at 11:33:09PM +0530, Subhashini Rao Beerisetty wrote: >>> Hi All, >>> >>> I'm currently looking for the Embedded USB Debug (EUD) interface driver. >> >> For what specific hardware? Do you have the needed "special" cable? We >> have support in the kernel for some types of these cables, what kernel >> versions have you tried that did not work for this? > It's for MSM hardware and yes we have the "special" cable. > I could not find the device driver for this in the mainline tree. It > would be helpful if you could point me to the kernel tree which > supports this feature. We will compile this suggested kernel and > necessary drivers and then will give a try on our hardware Hi, See USB_SERIAL_DEBUG in drivers/usb/serial/. That symbol builds usb_debug.c in that same directory. It may help to read Documentation/x86/earlyprintk.rst. My own cheat sheet (quick reference) says this: (it may or may not help you) (it might need some updating for XHCI): ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Using USB debug port (on a USB EHCI controller) On the system under test: CONFIG_USB_EHCI_HCD=y kernel command line: earlyprintk=dbgpN,keep With an XHCI controller, use: earlyprintk=xdbcN,keep Also add: console=tty0 or console=ttyUSB0 for console output to go to the serial port. Make sure that USB_SERIAL=y, USB_SERIAL_CONSOLE=y, and USB_SERIAL_DEBUG=y. ------ On the logging system: (requires CONFIG_USB_SERIAL_DEBUG=y) Run minicom and tell it to connect to /dev/ttyUSB#. Optionally have it log all messages to a file. ##### -- ~Randy