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=-5.2 required=3.0 tests=BAYES_00, 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 31159C4361A for ; Sat, 5 Dec 2020 20:49:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E5C46230F9 for ; Sat, 5 Dec 2020 20:49:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726028AbgLEUtd (ORCPT ); Sat, 5 Dec 2020 15:49:33 -0500 Received: from jabberwock.ucw.cz ([46.255.230.98]:37890 "EHLO jabberwock.ucw.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725379AbgLEUtb (ORCPT ); Sat, 5 Dec 2020 15:49:31 -0500 Received: by jabberwock.ucw.cz (Postfix, from userid 1017) id 326FA1C0B8D; Sat, 5 Dec 2020 21:48:35 +0100 (CET) Date: Sat, 5 Dec 2020 21:48:34 +0100 From: Pavel Machek To: Dmitry Torokhov List-Id: Cc: Linus Torvalds , Arnd Bergmann , Douglas Anderson , SoC Team , Linux ARM , Linux Kernel Mailing List Subject: Re: [GIT PULL] ARM: SoC fixes for v5.10, part 3 Message-ID: <20201205204834.GC8578@amd> References: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="8X7/QrJGcKSMr1RN" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --8X7/QrJGcKSMr1RN Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi! > > On Fri, Nov 27, 2020 at 12:51 PM Arnd Bergmann wrote: > > > > > > - Some DT patches for the Rockchip RK3399 platform, > > > in particular fixing the MMC device ordering that > > > recently became nondeterministic with async probe. > > > > Uhhuh. > > > > I didn't realize this MMC breakage happened. > > > > That's just an MMC bug. Other subsystems have been able to do async > > probing without making device ordering be random. > > > > So this really smells wrong, and I just never realized. > > > > Added Douglas Anderson to the cc - the whole PROBE_PREFER_ASYNCHRONOUS > > behavior appears broken. > > > > You basically should do the device numbering synchronously (or better > > yet - asynchronously, but single-threaded for the subsystem), and then > > asynchronously probe the actual device details after you've numbered > > them reliably. >=20 > Generally speaking it is either unnecessary for a lot of devices where > we do not care what number they get, harmful (why do I need to probe > i2c touchscreen and touchpad sequentially if I do not care which one > comes first but my boot will take 0.5 seconds longer if I serialize), > or impossible (if device is hit-pluggable). For many years userspace > has been moving away from static device assignments and we should not > be going back. Lets not make userspace's life harder than it should be. You can't break existing configurations, and people still use root=3D/dev/mmcblkX. Recently kernel on Droid 4 switched from MMC on mmcblk0 and mmcblk1 to MMC on mmcblk0 and mmcblk2. Of course that broke my config. And I'm fairly sure I'm not alone. (And it may not be this bug, and I do have workaround now.) Best regards, Pavel --=20 http://www.livejournal.com/~pavelmachek --8X7/QrJGcKSMr1RN Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAl/L8iIACgkQMOfwapXb+vJiEACgn18v+/EzhNIclf1Mh8seK6kI JIoAnikMuD1kNbKhB4/JxIujWDxJxAvD =Ro3a -----END PGP SIGNATURE----- --8X7/QrJGcKSMr1RN--