From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932478AbbJMOAm (ORCPT ); Tue, 13 Oct 2015 10:00:42 -0400 Received: from mail-qg0-f45.google.com ([209.85.192.45]:34657 "EHLO mail-qg0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932344AbbJMOAh (ORCPT ); Tue, 13 Oct 2015 10:00:37 -0400 Date: Tue, 13 Oct 2015 10:00:43 -0400 From: Tom Rini To: Nishanth Menon Cc: Lokesh Vutla , hs@denx.de, lkml , Arnd Bergmann , linux-mmc@vger.kernel.org, Dirk Behme , Georg.Soffel@bosch-si.com, linux-omap , Ulf Hansson , u-boot Subject: Re: [PATCH] mmc: omap_hsmmc: fix initialization order of mmc block devices Message-ID: <20151013140043.GT23893@bill-the-cat> References: <1444714193-24816-1-git-send-email-hs@denx.de> <561CA8D3.2090507@ti.com> <561CB653.5020707@denx.de> <561CBAE3.3020707@ti.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="nreWiX4Cj9hiu/Wx" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --nreWiX4Cj9hiu/Wx Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Oct 13, 2015 at 08:24:08AM -0500, Nishanth Menon wrote: > On Tue, Oct 13, 2015 at 3:03 AM, Lokesh Vutla wrote: > > > > > > On Tuesday 13 October 2015 01:14 PM, Heiko Schocher wrote: > >> Hello Lokesh, > >> > >> Am 13.10.2015 um 08:46 schrieb Lokesh Vutla: > >>> +Nishanth, > >>> > >>> On Tuesday 13 October 2015 10:59 AM, Heiko Schocher wrote: > >>>> On embedded devices, often there is a combination of > >>>> removable mmc devices (e.g. MMC/SD cards) and hard > >>>> wired ones (e.g. eMMC). Depending on the hardware > >>>> configuration, the 'mmcblkN' node might change if > >>>> the removable device is available or not at boot time. > >>>> > >>>> E.g. if the removable device is attached at boot time, > >>>> it might become mmxblk0. And the hard wired one mmcblk1. > >>>> But if the removable device isn't there at boot time, > >>>> the hard wired one will become mmcblk0. This makes it > >>>> somehow difficult to hard code the root device to the > >>>> non-removable device and boot fast. > >>> > >>> Why not use "root=3DPARTUUID=3D${uuid}" option instead of relying on > >>> mmcblk no? > >>> U-Boot can easily detect your partuuid. Refer to [1] on how TI platfo= rms > >>> does this in u-boot. > >> > >> Good tip ... I do not know, if it is possible to update U-Boot > >> on this boards... > >> > >> Current U-Boot says: > >> U-Boot 2013.01.01_heads/master-gc7900a0 (2015-05-06 - 20:37:15) > >> > >> I2C: ready > >> DRAM: 512 MiB > >> [...] > >> U-Boot# mmc rescan > >> U-Boot# mmc part > >> > >> Partition Map for MMC device 0 -- Partition Type: DOS > >> > >> Part Start Sector Num Sectors UUID Type > >> 1 63 144522 000ce343-01 0e Boot > >> 2 144585 659861 000ce343-02 83 > >> U-Boot# part uuid mmc 0:2 uuid > >> Unknown command 'part' - try 'help' > >> U-Boot# > >> > >> So, if this patch has no chance for mainline, please let me > >> know it, thanks! > >> > > > > IIRC, Nishanth had posted a patch something similar but got rejected for > > some reason. Probably Nishanth can comment more here. > > >=20 > overall the feedback I received was for block devices, there is > already an unique method(PARTUUID/uuid) of referencing required device > and mmcxblky aliasing was not really needed - hence dropped my patch > and switched over to partuuid. Not telling the kernel what to do here but root=3DPARTUUID=3D$x is the long standing portable multi-architecture (and storage medium) way to have a stable name for your root device. The automatic way of digging this information out in U-Boot is dates back to Sept 2012 in mainline. --=20 Tom --nreWiX4Cj9hiu/Wx Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iQIcBAEBAgAGBQJWHQ6LAAoJEIRElH1W1v7NWdsP/0kV/0vEKfnxUDxynyd/Gilc eXYNHXOgDWy9PH7KctM3GfG/TcW6elHv6bx9MZRCNJ2MeC5QNCcuQmBo+W8rYiRa 8h2qfsiHzXr6x0X0pZ6iIEsbDa0sexAaI01Bj4m7593O3ULziLd5uGuJbvd4qo/H fLQ1HSHbOpbaKQnwNMYpQH1T87ZkeWh5+vLShD4nhAjjhAvRC26nrWifwbkYlWJr nY41DUTsV8zRiXEvFgabiHQ6KHCu0VWgnwD8dSoIWbKrMTvx7fwfPUfbzsCfYtNA NGopcKQ3MzTlPi0wI8IBtMgWk2NElTL2PuOoJGRMju9AFMj19GcnpOjgiAQvgT9t HK5pd6OWgztMdC6JAKLHmXtlDId625yh9Qi+JdSGg0aflKfsE4CbELvI7B4AvQte bc8dY7c8T8wCKiMAPDaMyNknlWhH/idAVPzraglSpQ0gJHmx2kf8MPFBhNbyTOEL 84RjFwCOWOcbBdsJBeVoIdI5rM4OqJm/ztyYcq+HgFp+2V0JQH6fiYX3CLpUSXSb B2OSvWuRJcaRZIN1Swn6efLyGTPM+OIGzVB5k4sGZUBPbIIwVSj2L/dZE2hygi6F xMj0E9hTAbQkySaH7x+QoDE7SuYD8uf8WmJXLXN3zyfwpZ4Mz5mS4VwG85ywQa5O /pJnUytTnOM5bQO8A0y+ =hU8O -----END PGP SIGNATURE----- --nreWiX4Cj9hiu/Wx--