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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, 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 CA83FC433E1 for ; Thu, 14 May 2020 16:24:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9A539206D8 for ; Thu, 14 May 2020 16:24:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="OAPdlR0a" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726037AbgENQYu (ORCPT ); Thu, 14 May 2020 12:24:50 -0400 Received: from mail27.static.mailgun.info ([104.130.122.27]:18730 "EHLO mail27.static.mailgun.info" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725975AbgENQYt (ORCPT ); Thu, 14 May 2020 12:24:49 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1589473489; h=Content-Transfer-Encoding: Content-Type: In-Reply-To: MIME-Version: Date: Message-ID: From: References: Cc: To: Subject: Sender; bh=nVgMACd1zvIq4WhGfSju+6OvJNb61oG1e/CVzd4fVNc=; b=OAPdlR0aUGdRjmISPK65wTl8D4BQS8fHYbkX86UGFi3G+hOBTeEoLzS0z81GnY/vtGOtnQrJ +BroxJduzBXd6T1778xWMa8cbk+B5+aj50yOJYv68fWpRBroSyTo4dkAcjW9JlxTRpLN7Ksp yWWRwgVJuLEllIo7eLd4ooE8bxU= X-Mailgun-Sending-Ip: 104.130.122.27 X-Mailgun-Sid: WyI1MzIzYiIsICJsaW51eC1hcm0tbXNtQHZnZXIua2VybmVsLm9yZyIsICJiZTllNGEiXQ== Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by mxa.mailgun.org with ESMTP id 5ebd70cf.7f6d1a141ce0-smtp-out-n03; Thu, 14 May 2020 16:24:47 -0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 1001) id D542FC432C2; Thu, 14 May 2020 16:24:46 +0000 (UTC) Received: from [10.226.58.28] (i-global254.qualcomm.com [199.106.103.254]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: jhugo) by smtp.codeaurora.org (Postfix) with ESMTPSA id 982E6C433D2; Thu, 14 May 2020 16:24:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 982E6C433D2 Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=none smtp.mailfrom=jhugo@codeaurora.org Subject: Re: [RFC PATCH 3/8] qaic: Create char dev To: Greg KH Cc: arnd@arndb.de, manivannan.sadhasivam@linaro.org, bjorn.andersson@linaro.org, wufan@codeaurora.org, pratanan@codeaurora.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org References: <1589465266-20056-1-git-send-email-jhugo@codeaurora.org> <1589465266-20056-4-git-send-email-jhugo@codeaurora.org> <20200514141211.GA2643665@kroah.com> <0421a64a-10f3-08df-9ef1-14fdb570db0d@codeaurora.org> <20200514155615.GA2963499@kroah.com> From: Jeffrey Hugo Message-ID: <4be546d3-b571-0659-0140-f34ec88f95ff@codeaurora.org> Date: Thu, 14 May 2020 10:24:44 -0600 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200514155615.GA2963499@kroah.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On 5/14/2020 9:56 AM, Greg KH wrote: > On Thu, May 14, 2020 at 09:05:30AM -0600, Jeffrey Hugo wrote: >> Wow, thank you for the near immediate response. I'm am quite impressed. >> >> On 5/14/2020 8:12 AM, Greg KH wrote: >>> On Thu, May 14, 2020 at 08:07:41AM -0600, Jeffrey Hugo wrote: >>>> /* Copyright (c) 2019-2020, The Linux Foundation. All rights reserved. */ >>>> +#include >>>> +#include >>>> +#include >>>> +#include >>>> +#include >>>> #include >>>> #include >>>> +#include >>>> #include >>>> #include >>>> @@ -13,9 +19,242 @@ >>>> #define PCI_DEV_AIC100 0xa100 >>>> #define QAIC_NAME "Qualcomm Cloud AI 100" >>>> +#define QAIC_MAX_MINORS 256 >>> >>> Why have a max? >>> >>> Why not just use a misc device so you make the logic a lot simple, no >>> class or chardev logic to mess with at all. >> >> It was our understanding that the preference is not to add new misc devices. > > Huh, who said that? Not the char/misc maintainer (i.e. me) :) > >> As I go and try to find a supporting reference for that, I cannot find one, >> so I'm not entirely sure where that idea came from. >> >> In addition, we see that the Habana Labs driver also uses chardev, and has >> chosen the same max. We assumed that since their driver is already >> accepted, using the same mechanisms where applicable would be the preferred >> approach. > > They had good reasons why not to use a chardev and convinced me of it. > If you can't come up with them, then stick with a misc for now please. Interesting. I didn't see any discussion on this. >> Specific to the max, 256 was chosen as being a factor larger than the >> largest system we have, therefore we figured it wouldn't be hit for a long >> while even as we try to have a look at what might happen down the road. >> Looking at the Habana code, it looks like they have the same value for much >> of the same reasons, although their usecases may vary from ours somewhat. > > Max numbers for no good reason are not a good thing to have. > >> At this time, I don't think we have a strong requirement for a chardev, so >> we could investigate a switch over to a misc dev if you would prefer that >> over following the Habana Labs precedent. All I ask is a confirmation that >> is the approach you would like to see going forward after reviewing the >> above. > > Please use misc. Ok, will investigate. -- Jeffrey Hugo Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.