From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753132AbeEVU6b (ORCPT ); Tue, 22 May 2018 16:58:31 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:48526 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752937AbeEVU63 (ORCPT ); Tue, 22 May 2018 16:58:29 -0400 Date: Tue, 22 May 2018 22:58:26 +0200 From: Pavel Machek To: Aaro Koskinen Cc: Pali =?iso-8859-1?Q?Roh=E1r?= , sre@kernel.org, kernel list , linux-arm-kernel , linux-omap@vger.kernel.org, tony@atomide.com, khilman@kernel.org, ivo.g.dimitrov.75@gmail.com, patrikbachan@gmail.com, serge@hallyn.com, abcloriens@gmail.com, clayton@craftyguy.net, martijn@brixit.nl, sakari.ailus@linux.intel.com, Filip =?utf-8?Q?Matijevi=C4=87?= , Thorsten Leemhuis Subject: Re: v4.17-rc1: regressions on N900, N950 Message-ID: <20180522205824.GA24927@amd> References: <20180422074213.GA12428@amd> <20180423202940.ig6iud5lrbgnu35a@darkstar.musicnaut.iki.fi> <20180521213952.GA11596@amd> <20180522080250.4fzyvqrgw5oigexn@pali> <20180522194139.GB2299@darkstar.musicnaut.iki.fi> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="mYCpIKhGyMATD0i+" Content-Disposition: inline In-Reply-To: <20180522194139.GB2299@darkstar.musicnaut.iki.fi> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --mYCpIKhGyMATD0i+ Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue 2018-05-22 22:41:39, Aaro Koskinen wrote: > Hi, >=20 > On Tue, May 22, 2018 at 10:02:50AM +0200, Pali Roh=E1r wrote: > > Hi! I remember that in time of migration from platform board code to > > device tree structures there appeared some bug which caused that > > sometimes display were not initialized. And somebody figured out that > > display initialization is failing when some other SPI devices are > > initialized before or after display... This behavior was observed only > > on real N900 hardware, not in qemu. >=20 > Touchscreen needs to be initialized before display. This is documented > in the DTS, see arch/arm/boot/dts/omap3-n900.dts: >=20 > * For some reason, touchscreen is necessary for screen to work at > * all on real hw. It works well without it on emulator. > * > * Also... order in the device tree actually matters here. >=20 > > Real reason was never explained. In old platform board code there was > > hardcoded order of SPI devices in which initialization happened. And in > > device tree it is probably in (pseudo)-random order. Enabling/disabling > > various config option can affect some timings and order in which kernel > > starts probing and initializing devices... >=20 > The issue was also somewhat present with platform/board code, see e.g. > commit e65f131a14726e5f1b880a528271a52428e5b3a5. >=20 > My device worked with v4.17-rc1 (haven't found time to test newer kernels= ), > but if you say the probe order is random then we must find some proper way > to express the dependency. I started bisect, but.. that will probably not be useful. If your device works ok in v4.17-rc1, it probably works in newer -rcs, too. Thanks for the ordering hint, I'll try to figure out what is going on there. Pavel # bad: [60cc43fc888428bb2f18f08997432d426a243338] Linux 4.17-rc1 # good: [0adb32858b0bddf4ada5f364a84ed60b196dbcda] Linux 4.16 git bisect start 'v4.17-rc1' 'v4.16' # bad: [ac9053d2dcb9e8c3fa35ce458dfca8fddc141680] Merge tag 'usb-4.17-rc1' = of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb git bisect bad ac9053d2dcb9e8c3fa35ce458dfca8fddc141680 # bad: [bb2407a7219760926760f0448fddf00d625e5aec] Merge tag 'docs-4.17' of = git://git.lwn.net/linux git bisect bad bb2407a7219760926760f0448fddf00d625e5aec # bad: [1c7095d2836baafd84e596dd34ba1a1293a4faa9] Merge airlied/drm-next in= to drm-misc-next git bisect bad 1c7095d2836baafd84e596dd34ba1a1293a4faa9 --=20 (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo= g.html --mYCpIKhGyMATD0i+ Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAlsEhHAACgkQMOfwapXb+vKgAQCfRTCdEl9IB9Sl7HaxCaakO7cD 9sIAoJejrpAlCItIRa0bnoRqGJcFcvUC =fwvJ -----END PGP SIGNATURE----- --mYCpIKhGyMATD0i+--