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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 52F15C2D0CB for ; Thu, 12 Dec 2019 17:32:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2872C22B48 for ; Thu, 12 Dec 2019 17:32:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576171976; bh=d8T+W80ohSAutSwyvwOIJCoFk70VslbyWmhLhSjuY/o=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=s22pqKpxpEX3su5ZHy0OhCoz4cFtSIv3uK9ryBuAGnH608OSbbn+wqPfVIGimXCGn 6qop8X9xIonMrDEQdUCfbCG/rdxzcMNZ+AnpJloUMhP30+APctLrWNFJGbPHRPmzul gh72rbw/Ao43reXRzRI4YKMMWaYbrdDLMfQwQXJY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730183AbfLLRcz (ORCPT ); Thu, 12 Dec 2019 12:32:55 -0500 Received: from mail.kernel.org ([198.145.29.99]:37502 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730023AbfLLRcy (ORCPT ); Thu, 12 Dec 2019 12:32:54 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C21FA21655; Thu, 12 Dec 2019 17:32:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576171974; bh=d8T+W80ohSAutSwyvwOIJCoFk70VslbyWmhLhSjuY/o=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=f3WTTM5ez2jJGTd/r4ZgkBqS0RQv+WurCDZfPVTAe9IMbQVFSXPGEZ/4/oPfA+PLc 1HpYJVtHaQxCrhoZlvds+/CWRZStluyP0fTC8gN5/TQhnuz7SLcb54YCtcBgRW/ZqR k95AzqrkG069hz1bwHqMckyPeMKhD7tdGsmsMR6M= Date: Thu, 12 Dec 2019 18:32:51 +0100 From: Greg KH To: Vitor Soares Cc: "linux-kernel@vger.kernel.org" , "linux-i3c@lists.infradead.org" , Joao Pinto , "bbrezillon@kernel.org" , "wsa@the-dreams.de" , "arnd@arndb.de" , "broonie@kernel.org" Subject: Re: [RFC 5/5] i3c: add i3cdev module to expose i3c dev in /dev Message-ID: <20191212173251.GA1702856@kroah.com> References: <20191212144459.GB1668196@kroah.com> <20191212160045.GA1672362@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 12, 2019 at 05:25:28PM +0000, Vitor Soares wrote: > From: Greg KH > Date: Thu, Dec 12, 2019 at 16:00:45 > > > On Thu, Dec 12, 2019 at 02:56:56PM +0000, Vitor Soares wrote: > > > Hi Greg, > > > > > > From: Greg KH > > > Date: Thu, Dec 12, 2019 at 14:44:59 > > > > > > > On Tue, Dec 10, 2019 at 04:37:33PM +0100, Vitor Soares wrote: > > > > > +static int __init i3cdev_init(void) > > > > > +{ > > > > > + int res; > > > > > + > > > > > + pr_info("i3c /dev entries driver\n"); > > > > > > > > Please remove debugging information, kernel code should be quiet unless > > > > something goes wrong. > > > > > > I will remove it. > > > > > > > > > > > > + /* Dynamically request unused major number */ > > > > > + res = alloc_chrdev_region(&i3cdev_number, 0, N_I3C_MINORS, "i3c"); > > > > > > > > Do you really need a whole major, or will a few minors work? > > > > > > > > thanks, > > > > > > > > greg k-h > > > > > > I'm reserving one per device. What do you suggest? > > > > How many devices do you have in a system? > > According to MIPI I3C spec, the maximum number of devices on a bus will > depend on trace length, bus load, and clock requirements. > > Frankly, I don't know what is the best compromise because it depends from > system to system and the end-use of it. In my case, I started developing > this to help me during the HC controller driver development. > Even If I choose a fixed major, I wouldn't know in which one i3c fits. Ok, a full major will be fine, I was worried you only wanted 1 or 2 minor numbers, which would mean you could have used a misc device instead. This is fine. thanks, greg k-h