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=-5.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,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 05DCAC63777 for ; Mon, 30 Nov 2020 22:55:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9A83520725 for ; Mon, 30 Nov 2020 22:55:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="qBSfxuEs" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388682AbgK3Wzq (ORCPT ); Mon, 30 Nov 2020 17:55:46 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41844 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726520AbgK3Wzq (ORCPT ); Mon, 30 Nov 2020 17:55:46 -0500 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [IPv6:2001:4d48:ad52:32c8:5054:ff:fe00:142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EA745C0613D2 for ; Mon, 30 Nov 2020 14:55:05 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=FEehqEG1a1gUdHMKaEzZ631DuoSmxOdN1LmfoAyBjQc=; b=qBSfxuEsqEYHROB6wvqwA4hgO EH2hU26Pr7z9GnAYVIIn9mZLTPMgCr80jon+Fr0Wc9uwnXJezF0D7E086/eiUchvt5UY7NycIpwWC Untb1/3t8bDJt8i89ETNPxwwpmPOSSePmCN8OS6styfdvVLvio7JDgg3rXmO4R3X/O0i/tdSpSFUP FiRgdUeiGh61K1S5OEcBXo9DNtwZclHGar/+lEZHvMdGrofmgdkt369aTppCIGFU88/2aFW1oQwT2 1kaFMSCn04TZahWY79POLyVmeGthGE6VQIZ2MDyX9X/7NgUS2VKKavDhVNKqO8PGnTDvrSqIkZO3o yW14xwt6g==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:38174) by pandora.armlinux.org.uk with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1kjs4S-0007hl-FI; Mon, 30 Nov 2020 22:55:00 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1kjs4R-0005Ol-Ns; Mon, 30 Nov 2020 22:54:59 +0000 Date: Mon, 30 Nov 2020 22:54:59 +0000 From: Russell King - ARM Linux admin To: Linus Torvalds List-Id: Cc: Doug Anderson , Arnd Bergmann , SoC Team , Linux ARM , Linux Kernel Mailing List , Ulf Hansson , Dmitry Torokhov Subject: Re: [GIT PULL] ARM: SoC fixes for v5.10, part 3 Message-ID: <20201130225459.GB1551@shell.armlinux.org.uk> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: Russell King - ARM Linux admin Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 30, 2020 at 10:22:58AM -0800, Linus Torvalds wrote: > > I guess the question is: why is static assignment of numbers not an > > acceptable solution to the problem? It gives us the desired fixed > > numbers and automatically avoids all weird probe ordering / dependency > > problems. > > I think that if this had been done originally, it would probably be fine. It was not done originally, because the original structure of the MMC bus was: host controller ---+--- card 1 +--- card 2 +--- card 3 ... So one host controller could be connected to multiple different cards, and the bus has a way to detect each card individually. This means we had no idea how many cards would be connected to any one controller, and it was entirely sensible to allocate MMC block devices in the order we discovered the cards. The SD specification, this became limited to just one card per controller to allow for faster speeds. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!