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=-2.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 2826DC432BE for ; Sun, 15 Aug 2021 19:46:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0332561214 for ; Sun, 15 Aug 2021 19:46:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230175AbhHOTqy (ORCPT ); Sun, 15 Aug 2021 15:46:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37508 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229502AbhHOTqx (ORCPT ); Sun, 15 Aug 2021 15:46:53 -0400 Received: from mail-lf1-x12f.google.com (mail-lf1-x12f.google.com [IPv6:2a00:1450:4864:20::12f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4CE57C061764; Sun, 15 Aug 2021 12:46:22 -0700 (PDT) Received: by mail-lf1-x12f.google.com with SMTP id i28so3634107lfl.2; Sun, 15 Aug 2021 12:46:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=36NQvMA7IhQ2nmvYXvhQS10mXmbyiVfQYsSQBpwdN4E=; b=o9DHSf/Z8wa31i7vC39Q7BI4PvIDUQFrp3wSqcvy6IR4pNx1h5Y75KpRgXsK4zXz97 AhoBauG2YTmFnVlX94jAWt8u5on1Zdat77YdcOb8r0FXvo+IB0nSHp4d2pxOPfjWOXXC gCoTQQovqrXT9PFhsRvHgYsUB3lVBgH4Cl8iMiryt6IH9YR/KGAjpkiXBkoUTfuKUZ9d fEIpLmESp4jDdaX4ILeE+2FmDg7MsNnxXlYEgZdj2p2gTEhQHhe+w9yNNz3Lwgnnwcfn 4Xc2fWO54dJomMCfJn6F1LLjNAEK65eBo5c1v7G9xXbHSA4ax3ayCCLtlyQNpu5aP/za FwGQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=36NQvMA7IhQ2nmvYXvhQS10mXmbyiVfQYsSQBpwdN4E=; b=VytgKsLQ0K9Ycx4D0vl3FDuYDOW4lCL6gdnizjCYgVcLJYNNtZAWE1OiTB9LKHoFa5 JvidmQvoojf8goBeLVoXo/52rrKRkuymCYKXPQwplb0SG8NxyT2ybi2eWCDja7YfsUfC eRi6F8i30VAB58VfnrwTHL9YBT6OBj4X+pBgsC3Z91NfGYNcnmeuAl4oKTDPqlCY3129 wbO0hIH5pCnOREiLAshD9QraXS7+YDEN+nssmMMHhgZj0JrVPJ1Y9E8FFTAtlWd9uTyW OlASsrZBBlzmPC84K59RdvUO+2rQK5MZPQepzkNUQDJeWwZv00Ow6mBihHU6esoQvs1R 4wBA== X-Gm-Message-State: AOAM530WuJU7GLWbG4x+slN6Z7G//HiC69h64oobJ2Ox6ujFu4lUnmPt l17yn/Wpu9cx6kTERkGGgLo= X-Google-Smtp-Source: ABdhPJzares3O8HkMm6UoYb2Tt6v7dLiTqx4kl65ShpcTpWtLn4bm0L7MAaUy0Qh0nZbhc9gchSvUg== X-Received: by 2002:ac2:4833:: with SMTP id 19mr9273501lft.528.1629056780602; Sun, 15 Aug 2021 12:46:20 -0700 (PDT) Received: from mobilestation ([95.79.127.110]) by smtp.gmail.com with ESMTPSA id s4sm932870ljp.115.2021.08.15.12.46.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 15 Aug 2021 12:46:19 -0700 (PDT) Date: Sun, 15 Aug 2021 22:46:17 +0300 From: Serge Semin To: John Stultz Cc: Serge Semin , Bjorn Andersson , Krzysztof Kozlowski , Greg Kroah-Hartman , Rob Herring , Felipe Balbi , Florian Fainelli , Andy Gross , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , linux-arm-msm , Linux USB List , lkml , linux-arm-kernel , Amit Pundir Subject: Re: [PATCH 29/29] arm64: dts: qcom: Harmonize DWC USB3 DT nodes name Message-ID: <20210815194617.sbrkutxzldqbxfat@mobilestation> References: <0064cb2c-5ca6-e693-2e89-8f045c8f7502@kernel.org> <20210721112531.xvu6ni5ksaehsrjh@mobilestation> <20210722181221.xh3r5kyu7zlcojjx@mobilestation> <20210722220918.l7j6zw3aaa27qato@mobilestation> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org Hello John On Fri, Aug 13, 2021 at 06:06:24PM -0700, John Stultz wrote: > On Thu, Jul 22, 2021 at 3:09 PM Serge Semin wrote: > > On Thu, Jul 22, 2021 at 01:09:05PM -0700, John Stultz wrote: > > > On Thu, Jul 22, 2021 at 12:17 PM Bjorn Andersson > > > wrote: > > > > > On Jul 21, 2021, 1:45 PM +0200, Krzysztof Kozlowski wrote: > > > > > > I had impression that kernel defines interfaces which should be used and > > > > > > are stable (e.g. syscalls, sysfs and so on). This case is example of > > > > > > user-space relying on something not being marked as part of ABI. Instead > > > > > > they found something working for them and now it is being used in "we > > > > > > cannot break existing systems". Basically, AOSP unilaterally created a > > > > > > stable ABI and now kernel has to stick to it. > > > > > > > > > > > > Really, all normal systems depend on aliases or names and here we have > > > > > > dependency on device address. I proposed way how AOSP should be fixed. > > > > > > Anything happened? Nope. > > > > > > > > > > First time he sent a possible solution for the problem: > > > > > https://lore.kernel.org/lkml/20201221210423.GA2504@kozik-lap/ > > > > > > > > > > To sum up you could have used one of the more portable approaches > > > > > 1. add an udc alias to the controller and use it then to refer to the > > > > > corresponding USB controller > > > > > > > > Is there such a thing as "UDC alias"? Or are you suggesting that we > > > > should add such feature? > > > > > > > > I think it would be wonderful if we could identify the UDCs on our > > > > boards as "USB1" and "USB2", or "the one and only USB-C connector". But > > > > unless that will fall back to the existing naming it would break John's > > > > _existing_ userspace. > > > > > > > > Well, I'd not hold up the existing userspace I'm using as sacrosanct > > > (AOSP devices still usually don't have to work cross-kernel versions - > > > devboards being the main exception). I'm fine if we can rework > > > userland as proposed, so that the issues can be avoided, but I > > > honestly don't have enough context to really understand what that > > > looks like (no idea what udc aliases are). > > > > > > And whatever we do, the main constraint is that userland has to be > > > able to work with existing LTS kernels and newer kernels. > > > > As I said in my response to Bjorn even if it is added to the kernel it > > won't get to the official LTSes as it would be a new kernel feature. > > New features aren't normally backported to the older kernels. > > > > > > > > > > 2. search through DT-nodes looking for a specific compatible/reg > > > > > DT-properties. > > > > > > > > > > > > > We could define that this is the way, but again we didn't yesterday so > > > > your proposal is not backwards compatible. > > > > > > > > It may be backwards compatible, but I'm still not clear exactly how it > > > would work. > > > > > > I guess if we look through all > > > sys/bus/platform/devices/*/of_node/compatbile strings for the desired > > > "snps,dwc3", then find which of the directories have the desired > > > address in the string? (The suggestion for looking at reg seems > > > better, but I don't get a char value out of the dwc3 of_node/reg > > > file). > > > > The algorithm is simple: > > 1) You know what USB controllers you have on your platform. They are > > supposed to be compatible with snps,dwc3 string and have some pre-defined > > base address. > > 2) Find all the files in the directory /sys/class/udc/. > > 3) Walk through all the directories in /sys/bus/platform/devices/ with > > names found in 2) and stop on the device with matching compatible/base > > address defined in 1). > > > > In my case the strings could be retrieved like this: > > USB_NAME_COMPAT=$(/sys/bus/platform/devices/1f100000.usb/of_node/compatible | tr '\0' '\t' | cut -f1) > > USB_DEVICE_ADDR="$(head -c 4 /sys/bus/platform/devices/1f100000.usb/of_node/reg | hexdump -ve '/1 "%02x"' | sed -e 's/^0*//g')" > > > Hey Serge, > I just wanted to follow up here. Amit has reworked the db845c AOSP > userland so that it no longer uses the fixed node name, but instead > probes for it: > https://android-review.googlesource.com/c/device/linaro/dragonboard/+/1774872 > > Admittedly, it does take a short-cut. As your algorithm above, > digging up the devices and finding the sys/bus path to read the reg > value and pipe through hexdump (which android doesn't have) seemed > overly obtuse when the address is in the node name itself (while the > only way to be sure, one normally doesn't use spectroscopy to > determine the value of a coin when you can read what's printed on it > :). But, should the node naming be further changed at least the > infrastructure we have can be reworked fairly easily to adapt now. > > In any case, as we can handle the name change now, if you want to > resubmit your patch, we would no longer object (but can't promise no > one else might be bitten). Sorry for the delay this caused, and we > appreciate you working with us to find a solution. Great! Thanks for sending the notification. I'll resend the patch with a reference to your report and to the update made to AOSP, as soon as I am done with my current task. Regards -Sergey > > thanks > -john