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 2E2EFC433DF for ; Sat, 16 May 2020 21:29:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EF1E120756 for ; Sat, 16 May 2020 21:29:38 +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="WrC8AIXq" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726674AbgEPV3i (ORCPT ); Sat, 16 May 2020 17:29:38 -0400 Received: from mail26.static.mailgun.info ([104.130.122.26]:42873 "EHLO mail26.static.mailgun.info" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726671AbgEPV3i (ORCPT ); Sat, 16 May 2020 17:29:38 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1589664577; h=Content-Transfer-Encoding: Content-Type: In-Reply-To: MIME-Version: Date: Message-ID: From: References: Cc: To: Subject: Sender; bh=yyI11KWmcGi5NQVxIZYxF6jFoW7UiVn3lFSVRfQoiBk=; b=WrC8AIXqJAgz/3P6sRCckI7HnbQZ/9oZUneCAItSG+Gh8ZatgLlZdNzgZA2JsbiD4bjot0Iy bLbcW0efwUZS+MDF34kK5PoYkPCBzQV6pJtjcJccPhkUkzdVhtW4B+pDRwu14j0ZioAS/7dL xLu2N/tNHJGabnRobCXmDpi6VCA= 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 5ec05b33.7f0270f4d1b8-smtp-out-n04; Sat, 16 May 2020 21:29:23 -0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 1001) id AA65AC43637; Sat, 16 May 2020 21:29:22 +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 60A3AC433D2; Sat, 16 May 2020 21:29:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 60A3AC433D2 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> From: Jeffrey Hugo Message-ID: <8e06c718-8b8a-f09a-4685-11c0c1581a0c@codeaurora.org> Date: Sat, 16 May 2020 15:29:19 -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: <20200516070131.GB3964535@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 5/16/2020 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? -- Jeffrey Hugo Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.