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 C3D02C433DF for ; Thu, 14 May 2020 15:05:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 99CF9206A5 for ; Thu, 14 May 2020 15:05:43 +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="f/AyvLO2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726232AbgENPFm (ORCPT ); Thu, 14 May 2020 11:05:42 -0400 Received: from mail26.static.mailgun.info ([104.130.122.26]:13759 "EHLO mail26.static.mailgun.info" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726707AbgENPFl (ORCPT ); Thu, 14 May 2020 11:05:41 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1589468740; h=Content-Transfer-Encoding: Content-Type: In-Reply-To: MIME-Version: Date: Message-ID: From: References: Cc: To: Subject: Sender; bh=QuugbqXLqjwV0KyQWSSDk5Lob1gOR+ZMDHMsKv9tiKY=; b=f/AyvLO2ypG7R36hDrHw50hqwBKiQkzEr/xjP8elWZ/YiHIATIox5f/QqcTZ7npM3gcUIIrq bLVZMsqW3kFlLgq7SQi38FmewBUJoZH+7kD4qFc+GZQrra+AAzdcCAXQ6V5aX/xh+VNEXZD6 bsFhhrU6fS47xuOPFYo0Vlxr1PE= X-Mailgun-Sending-Ip: 104.130.122.26 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 5ebd5e3c.7f582983b6c0-smtp-out-n04; Thu, 14 May 2020 15:05:32 -0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 5F0CDC43636; Thu, 14 May 2020 15:05:32 +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 4626DC433D2; Thu, 14 May 2020 15:05:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 4626DC433D2 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> From: Jeffrey Hugo Message-ID: <0421a64a-10f3-08df-9ef1-14fdb570db0d@codeaurora.org> Date: Thu, 14 May 2020 09:05:30 -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: <20200514141211.GA2643665@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 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. 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. 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. 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. -- Jeffrey Hugo Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.