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=-1.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_PASS 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 F1253C6786C for ; Fri, 14 Dec 2018 11:13:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B2800208E7 for ; Fri, 14 Dec 2018 11:13:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ti.com header.i=@ti.com header.b="ralRyThW" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B2800208E7 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=ti.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729462AbeLNLNh (ORCPT ); Fri, 14 Dec 2018 06:13:37 -0500 Received: from lelv0142.ext.ti.com ([198.47.23.249]:53828 "EHLO lelv0142.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726281AbeLNLNg (ORCPT ); Fri, 14 Dec 2018 06:13:36 -0500 Received: from fllv0034.itg.ti.com ([10.64.40.246]) by lelv0142.ext.ti.com (8.15.2/8.15.2) with ESMTP id wBEBDT0C120637; Fri, 14 Dec 2018 05:13:29 -0600 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1544786009; bh=LgDbleTPzqepNQfg+C0pn1INv0Xfe4g292FVb2TeZ2s=; h=Subject:To:CC:References:From:Date:In-Reply-To; b=ralRyThWzZWipFz7xqy+LAnNkAVPxf35YjRdFkquwlbXQth8yErW0GeoIROjwkmyR zkOCQq5gk4ZSqsBaPGIK86BrSB7nOxerTJIpqA531Jm1aykqjtaEonkLXaiFQSDwSw PHfyUuJXTV8FB4B6tZsn3zRjq3MOG6r5fT9j5js0= Received: from DLEE115.ent.ti.com (dlee115.ent.ti.com [157.170.170.26]) by fllv0034.itg.ti.com (8.15.2/8.15.2) with ESMTPS id wBEBDTsJ113247 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Fri, 14 Dec 2018 05:13:29 -0600 Received: from DLEE111.ent.ti.com (157.170.170.22) by DLEE115.ent.ti.com (157.170.170.26) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1591.10; Fri, 14 Dec 2018 05:13:29 -0600 Received: from dflp32.itg.ti.com (10.64.6.15) by DLEE111.ent.ti.com (157.170.170.22) with Microsoft SMTP Server (version=TLS1_0, cipher=TLS_RSA_WITH_AES_256_CBC_SHA) id 15.1.1591.10 via Frontend Transport; Fri, 14 Dec 2018 05:13:29 -0600 Received: from [172.24.190.172] (ileax41-snat.itg.ti.com [10.172.224.153]) by dflp32.itg.ti.com (8.14.3/8.13.8) with ESMTP id wBEBDONL003013; Fri, 14 Dec 2018 05:13:25 -0600 Subject: Re: [RFC PATCH v2 08/15] usb:cdns3: Implements device operations part of the API To: Felipe Balbi , Peter Chen , CC: , , Greg Kroah-Hartman , , lkml , , , , , , , References: <1542535751-16079-1-git-send-email-pawell@cadence.com> <1542535751-16079-9-git-send-email-pawell@cadence.com> <5BFE8883.7090802@ti.com> <6b19b55c-66d7-439e-df8f-7b311b45af5e@ti.com> <5a41de27-cd1f-0cfd-ccdc-dccbf0854fcb@ti.com> <87bm5ol6zt.fsf@linux.intel.com> From: Sekhar Nori Message-ID: Date: Fri, 14 Dec 2018 16:43:24 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <87bm5ol6zt.fsf@linux.intel.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8bit X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Felipe, On 14/12/18 4:17 PM, Felipe Balbi wrote: > Hi, > > Sekhar Nori writes: > > > >>>>> All this should be part of comments in code along with information about >>>>> controller versions which suffer from the errata. >>>>> >>>>> Is there a version of controller available which does not have the >>>>> defect? Is there a future plan to fix this? >>>>> >>>>> If any of that is yes, you probably want to handle this with runtime >>>>> detection of version (like done with DWC3_REVISION_XXX macros). >>>>> Sometimes the hardware-read versions themselves are incorrect, so its >>>>> better to introduce a version specific compatible too like >>>>> "cdns,usb-1.0.0" (as hinted to by Rob Herring as well). >>>>> >>>> >>>> custom match_ep is used and works with all versions of the gen1 >>>> controller. Future (gen2) releases of the controller won’t have such >>>> limitation but there is no plan to change current (gen1) functionality >>>> of the controller. >>>> >>>> I will add comment before cdns3_gadget_match_ep function. >>>> Also I will change cdns,usb3 to cdns,usb3-1.0.0 and add additional >>>> cdns,usb3-1.0.1 compatible. >>>> >>>> cdns,usb3-1.0.1 will be for current version of controller which I use. >>>> cdns,usb3-1.0.0 will be for older version - Peter Chan platform. >>>> I now that I have some changes in controller, and one of them require >>>> some changes in DRD driver. It will be safer to add two separate >>>> version in compatibles. >>>> >>> >>> Pawel, could we have correct register to show controller version? It is >>> better we could version judgement at runtime instead of static compatible. >> >> Agree with detecting IP version at runtime. >> >> But please have some indication of version in compatible string too, > > why? Runtime detection by revision register should be the way to go if > the HW provides it. Why duplicate the information in compatible string? > >> especially since you already know there is going to be another revision >> of hardware. It has the advantage that one can easily grep to see which >> hardware is running current version of controller without having access >> to the hardware itself. Becomes useful later on when its time to >> clean-up unused code when boards become obsolete or for requesting >> testing help. > > This doesn't sound like a very strong argument, actually. Specially when > you consider that, since driver will do revision checking based on > revision register, you already have strings to grep. Moreover, we don't > usually drop support just like that. AFAICS, it is impossible to know just by grep'ing if there is any hardware still supported in kernel and using DWC3_REVISION_194A, for example. If we are never going to drop support for any revision, this does not matter much. Also, once you have the controller supported behind PCI, then I guess you are pretty much tied to having to read hardware revision at runtime. > Personally, I wouldn't bother. Just like dwc3 never bothered and nothing > bad came about because of it. Well, there are quirks which are > undetectable and for those we have quirk flags. I much prefer that > arrangement. Yes, quirk flags will work too for undetectable quirks. Thanks, Sekhar