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=-2.1 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 4A337C433DF for ; Sun, 17 May 2020 19:37:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 286E920657 for ; Sun, 17 May 2020 19:37:26 +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="T04bod5n" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726299AbgEQThZ (ORCPT ); Sun, 17 May 2020 15:37:25 -0400 Received: from mail27.static.mailgun.info ([104.130.122.27]:14570 "EHLO mail27.static.mailgun.info" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726271AbgEQThZ (ORCPT ); Sun, 17 May 2020 15:37:25 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1589744244; h=Content-Transfer-Encoding: Content-Type: In-Reply-To: MIME-Version: Date: Message-ID: From: References: Cc: To: Subject: Sender; bh=CsqgeE+faSNQ00Ax1SuNjJJHtZAQakq3R2LnrPY8eDk=; b=T04bod5n+ER7Kecz4wzEbvxpWrwwHIZneOx7pqt686VoHVqXmSRdI0VIDJfBRbXmTezducg1 uYUtXad/RATrTp9hBUI63MxfTV/735NnWIWkQVZF9UTlwMyBQ+W0ixi/dh9nXwmeGaIIbh6S 7mhUALHkEsa92T5nxPoPBRgmka8= 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 smtp-out-n05.prod.us-east-1.postgun.com with SMTP id 5ec192748ebbf95ecb84825c (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Sun, 17 May 2020 19:37:24 GMT Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 890DFC432C2; Sun, 17 May 2020 19:37:23 +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 6F53FC433F2; Sun, 17 May 2020 19:37:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 6F53FC433F2 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> <4be546d3-b571-0659-0140-f34ec88f95ff@codeaurora.org> <4683046a-c6b5-30a5-ef02-2f610523ae1c@codeaurora.org> <20200516070131.GB3964535@kroah.com> <8e06c718-8b8a-f09a-4685-11c0c1581a0c@codeaurora.org> <20200517071417.GA3090070@kroah.com> From: Jeffrey Hugo Message-ID: <46581ccf-9cd4-3b9f-9b03-ed1264dac03b@codeaurora.org> Date: Sun, 17 May 2020 13:37:20 -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: <20200517071417.GA3090070@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 5/17/2020 1:14 AM, Greg KH wrote: > On Sat, May 16, 2020 at 03:29:19PM -0600, Jeffrey Hugo wrote: >> On 5/16/2020 1:01 AM, Greg KH wrote: >>> On Fri, May 15, 2020 at 03:08:59PM -0600, Jeffrey Hugo wrote: >>>> 2. There are a limited number of dynamic minor numbers for misc devs (64), >>>> so if you are expecting more devices than that, a misc dev is not >>>> appropiate. Also, these minors are shared with other misc dev users, so >>>> depending on the system configuration, you might have significantly less >>>> than 64 minors available for use. >>> >>> I'm pretty sure we can have more than 64 misc devices, that limitation >>> should have been removed a while ago. Try it and see :) >> >> In total, there can be more tha 64 misc devices. However my previous >> comment was specific to dynamic minors (ie devices which do not have an >> assigned minor). The limit on dynamic minors still apears to be 64. Looking >> at the code - >> >> DYNAMIC_MINORS is still 64 >> https://elixir.bootlin.com/linux/v5.7-rc5/source/drivers/char/misc.c#L63 >> >> I see the same in -next >> >> DYNAMIC_MINORS is used to size a bitmap - one bit for each dynamic minor >> misc device that exists at one particular point in time. After all 64 bits >> are consumed by misc_register() by clients requesting a dynamic minor, no >> more dynamic minor misc devices can be registered until some are >> unregistered. >> >> What am I missing? > > Oops, nothing, my fault. We fixed up the allocation of more dynamic > majors for chardev in 2017 and for some reason I thought we also > increased the number of misc dynamic minors at the same time, but that > was incorrect. No problem. > I'll gladly take patches that bump up the number of misc minors if > needed. I don't think its needed at this time, but I will keep that in mind. > But to get back to the main issue here, you are only going to have 1 or > maybe 2 of these devices in a system at a time, right? So "burning" a > whole major number for that feels like a waste. Depends on what the customer wants to do. We support a number of systems, but one in particular has the capability of 6-12 devices. -- Jeffrey Hugo Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.