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=-5.6 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 CD25DC43387 for ; Thu, 10 Jan 2019 12:54:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8B1A02173B for ; Thu, 10 Jan 2019 12:54:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ti.com header.i=@ti.com header.b="kzG8JsSK" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728694AbfAJMyo (ORCPT ); Thu, 10 Jan 2019 07:54:44 -0500 Received: from fllv0015.ext.ti.com ([198.47.19.141]:41444 "EHLO fllv0015.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726974AbfAJMyn (ORCPT ); Thu, 10 Jan 2019 07:54:43 -0500 Received: from lelv0266.itg.ti.com ([10.180.67.225]) by fllv0015.ext.ti.com (8.15.2/8.15.2) with ESMTP id x0ACsXPJ077628; Thu, 10 Jan 2019 06:54:33 -0600 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1547124873; bh=5R7lfVR8rPCMRXwapD+fdMf/I7r2EXKypS9DQwn4Spo=; h=Subject:To:CC:References:From:Date:In-Reply-To; b=kzG8JsSK45do1MfuLuqemmIAXy+0QLMyHecZK5XKp3FaJflLwWH0iUEtZBjlwetgR Dt5ADw+erZxd0LhhwRT1/cm3F6EJUh7m9ugi+K1rguuYMhoNPFi3eQifsl1bbOnSb7 DojzmZ55FQEWCF4rliIa9AT1VYWs5bICCqtjK3pk= Received: from DLEE111.ent.ti.com (dlee111.ent.ti.com [157.170.170.22]) by lelv0266.itg.ti.com (8.15.2/8.15.2) with ESMTPS id x0ACsXHo072744 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Thu, 10 Jan 2019 06:54:33 -0600 Received: from DLEE114.ent.ti.com (157.170.170.25) by DLEE111.ent.ti.com (157.170.170.22) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1591.10; Thu, 10 Jan 2019 06:54:33 -0600 Received: from dflp32.itg.ti.com (10.64.6.15) by DLEE114.ent.ti.com (157.170.170.25) with Microsoft SMTP Server (version=TLS1_0, cipher=TLS_RSA_WITH_AES_256_CBC_SHA) id 15.1.1591.10 via Frontend Transport; Thu, 10 Jan 2019 06:54:33 -0600 Received: from [172.22.122.36] (ileax41-snat.itg.ti.com [10.172.224.153]) by dflp32.itg.ti.com (8.14.3/8.13.8) with ESMTP id x0ACsX8H030689; Thu, 10 Jan 2019 06:54:33 -0600 Subject: Re: [RFC PATCH 1/3] can: m_can: Create m_can core to leverage common code To: "Rizvi, Mohammad Faiz Abbas" , Wolfgang Grandegger , , CC: , , References: <20181010142055.25271-1-dmurphy@ti.com> <20181010142055.25271-2-dmurphy@ti.com> <52811b27-00c0-f5e2-2b18-608ccf846723@grandegger.com> <349ef8be-f4c7-25cc-2c33-7ce1fd0b0f40@ti.com> <9003a544-83cf-7dce-7f14-4abd292d470e@grandegger.com> <69d3a046-2d55-06e0-fba7-c9a0d20e6daa@grandegger.com> <62dd2f40-3ef6-fa6d-dc53-6896b52020ca@ti.com> From: Dan Murphy Message-ID: <0fb5e9a8-614b-44db-0d89-e675e28bbe92@ti.com> Date: Thu, 10 Jan 2019 06:54:22 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.3 MIME-Version: 1.0 In-Reply-To: <62dd2f40-3ef6-fa6d-dc53-6896b52020ca@ti.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 Faiz On 1/10/19 1:57 AM, Rizvi, Mohammad Faiz Abbas wrote: > Hi Dan, Wolfgang, > > On 1/10/2019 1:14 PM, Wolfgang Grandegger wrote: >> Hello Dan, >> >> sorry for my late response on that topic... >> >> Am 09.01.19 um 21:58 schrieb Dan Murphy: >>> Wolfgang >>> >>> On 11/3/18 5:45 AM, Wolfgang Grandegger wrote: >>>> Hello Dan, >>>> >>>> Am 31.10.2018 um 21:15 schrieb Dan Murphy: >>>>> Wolfgang >>>>> >>>>> Thanks for the review >>>>> >>>>> On 10/27/2018 09:19 AM, Wolfgang Grandegger wrote: >>>>>> Hello Dan, >>>>>> >>>>>> for the RFC, could you please just do the necessary changes to the >>>>>> existing code. We can discuss about better names, etc. later. For >>>>>> the review if the common code I quickly did: >>>>>> >>>>>>    mv m_can.c m_can_platform.c >>>>>>    mv m_can_core.c m_can.c >>>>>> >>>>>> The file names are similar to what we have for the C_CAN driver. >>>>>> >>>>>>    s/classdev/priv/ >>>>>>    variable name s/m_can_dev/priv/ >>>>>> >>>>>> Then your patch 1/3 looks as shown below. I'm going to comment on that >>>>>> one. The comments start with "***".... >>>>>> >>>>> >>>>> So you would like me to align the names with the c_can driver? >>>> >>>> That would be the obvious choice. >>>>> >>>>>> >>>>>> *** I didn't review the rest of the patch for now. >>>>>> >>>>> >>>>> snipped the code to reply to the comment. >>>>> >>>>>> Looking to the generic code, you didn't really change the way >>>>>> the driver is accessing the registers. Also the interrupt handling >>>>>> and rx polling is as it was before. Does that work properly using >>>>>> the SPI interface of the TCAN4x5x? >>>>> >>>>> I don't want to change any of that yet.  Maybe my cover letter was not clear >>>>> or did not go through. >>>>> >>>>> But the intention was just to break out the functionality to create a MCAN framework >>>>> that can be used by devices that contain the Bosch MCAN core and provider their own protocal to access >>>>> the registers in the device. >>>>> >>>>> I don't want to do any functional changes at this time on the IP code itself until we have a framework. >>>>> There should be no regression in the io mapped code. >>>>> >>>>> I did comment on the interrupt handling and asked if a threaded work queue would affect CAN timing. >>>>> For the original TCAN driver this was the way it was implemented. >>>> >>>> Do threaded interrupts with RX polling make sense? I think we need a >>>> common interface allowing to select hard-irqs+napi or threaded-irqs. >>>> >>> >>> I have been working on this code for about a month now and I am *not happy* with the amount of change that needs >>> to be done to make the m_can a framework. >>> >>> I can tx/rx frames from another CAN device to the TCAN part but I have not even touched the iomapped code. >>> >>> The challenging part is that the m_can code that is currently available does not have to worry about atomic context because >>> there is no peripheral waiting.  Since the TCAN is a peripheral device we need to take into about the hard waits in IRQ context >>> as well as the atomic context.  Doing this creates many deltas in the base code that may break iomapped devices.  I have had to >>> add the thread_irqs and now I am in the midst of the issue you brought up with napi.  I would have to schedule a queue for perp devices >>> and leave the non-threaded iomapped irq. >>> >>> At this point I think it may be wise to leave the m_can code alone as it is working and stable and just work on the TCAN driver as >>> a standalone driver.  A framework would be nice but I think it would destablize the m_can driver which is embedded in many SoC's and >>> we cannot possibly test everyone of them. >> >> Unfortunately, I do not have m_can hardware at hand. > > There are exactly 3 platforms in mainline that use the m_can driver. I can help Dan test it on a dra76x. I haven't had a chance to look at the changes in depth, but just testing for regressions on existing platforms shouldn't be too hard once we have it working on one. > Thanks Faiz. Once I have the TCAN fully working I will post the branch to my repo. Dan > Thanks, > Faiz > >> >>> What are your thoughts? >> >> What we need is a common set of functions doing tx, rx, error and state >> handling. This will requires substantial changes to the existing >> io-mapped m_can driver, of course. I still believe it's worth the >> effort, but I agree that it's difficult for you to re-write and test the >> existing m_can driver. >> >> What about implementing such a set of common functions plus the SPI >> specific part for your TCAN device. What do you/others think? >> >> Wolfgang. >> -- ------------------ Dan Murphy