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,URIBL_BLOCKED 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 B8F23C67839 for ; Fri, 14 Dec 2018 12:21:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 748DF20879 for ; Fri, 14 Dec 2018 12:21:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ti.com header.i=@ti.com header.b="x8iCVB+h" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 748DF20879 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 S1732471AbeLNMVJ (ORCPT ); Fri, 14 Dec 2018 07:21:09 -0500 Received: from fllv0016.ext.ti.com ([198.47.19.142]:39796 "EHLO fllv0016.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730818AbeLNMVH (ORCPT ); Fri, 14 Dec 2018 07:21:07 -0500 Received: from lelv0266.itg.ti.com ([10.180.67.225]) by fllv0016.ext.ti.com (8.15.2/8.15.2) with ESMTP id wBECL1OA098672; Fri, 14 Dec 2018 06:21:01 -0600 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1544790061; bh=ePnv9HQ3UvQmiB4iUx9pT5n0ArMcegklokOjL0e1ydY=; h=Subject:To:CC:References:From:Date:In-Reply-To; b=x8iCVB+h3FbqaThYNsMg7tfnW55foqGNteCrFM3akEwk71pSHkmpaODm9AiPYY7Mm yxuSXzVSQ+8wrIqZEHk0k52CktlXre8UimliIaZb1g2SMqhs55uOhGBRBIZNfGujmp GLUGv4q9hm4OhfGJ+xJ6d/NwyomJSk45LaKFvQvc= Received: from DFLE110.ent.ti.com (dfle110.ent.ti.com [10.64.6.31]) by lelv0266.itg.ti.com (8.15.2/8.15.2) with ESMTPS id wBECL0NN030790 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Fri, 14 Dec 2018 06:21:00 -0600 Received: from DFLE103.ent.ti.com (10.64.6.24) by DFLE110.ent.ti.com (10.64.6.31) 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 06:21:00 -0600 Received: from dflp33.itg.ti.com (10.64.6.16) by DFLE103.ent.ti.com (10.64.6.24) 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 06:21:00 -0600 Received: from [172.24.190.172] (ileax41-snat.itg.ti.com [10.172.224.153]) by dflp33.itg.ti.com (8.14.3/8.13.8) with ESMTP id wBECKtSq028107; Fri, 14 Dec 2018 06:20:56 -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> <875zvwl585.fsf@linux.intel.com> From: Sekhar Nori Message-ID: <7e6ac47e-61e4-ecd3-73d3-9b1be2d81479@ti.com> Date: Fri, 14 Dec 2018 17:50:55 +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: <875zvwl585.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 On 14/12/18 4:56 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. > > but why do you even care? When, for example, its coming in the way of some clean-up I am attempting to do. > >> 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. > > that's another argument *for* using runtime detection, not against it. I know :). I should have stated that in last e-mail itself, I am okay with just runtime detection. Thanks, Sekhar