Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754018Ab3IQWZo (ORCPT ); Tue, 17 Sep 2013 18:25:44 -0400 Received: from metis.ext.pengutronix.de ([92.198.50.35]:45017 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753147Ab3IQWZn (ORCPT ); Tue, 17 Sep 2013 18:25:43 -0400 Message-ID: <5238D6BE.6040603@pengutronix.de> Date: Wed, 18 Sep 2013 00:25:02 +0200 From: Marc Kleine-Budde User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130518 Icedove/17.0.5 MIME-Version: 1.0 To: Thomas Gleixner CC: Ludovic Desroches , Russell King - ARM Linux , nicolas.ferre@atmel.com, LKML , Marc Pignat , john.stultz@linaro.org, kernel@pengutronix.de, Ronald Wahl , LAK , =?UTF-8?B?VXdlIEtsZWluZS1Lw7Y=?= =?UTF-8?B?bmln?= Subject: Re: [PATCH] clockevents: Sanitize ticks to nsec conversion References: <1379077365-18458-1-git-send-email-mkl@pengutronix.de> <20130917095600.GJ26819@ludovic.desroches@atmel.com> <20130917100417.GQ12758@n2100.arm.linux.org.uk> <20130917130153.GL26819@ludovic.desroches@atmel.com> In-Reply-To: X-Enigmail-Version: 1.5.2 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="lXvI9XfF7mgXCgDbuVn0cQiKUs2rrQQ7E" X-SA-Exim-Connect-IP: 2001:6f8:1178:4:5054:ff:fe8d:eefb X-SA-Exim-Mail-From: mkl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2231 Lines: 55 This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --lXvI9XfF7mgXCgDbuVn0cQiKUs2rrQQ7E Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 09/17/2013 11:15 PM, Thomas Gleixner wrote: > Marc Kleine-Budde pointed out, that commit 77cc982 "clocksource: use > clockevents_config_and_register() where possible" caused a regression > for some of the converted subarchs. >=20 > The reason is, that the clockevents core code converts the minimal > hardware tick delta to a nanosecond value for core internal > usage. This conversion is affected by integer math rounding loss, so > the backwards conversion to hardware ticks will likely result in a > value which is less than the configured hardware limitation. The > affected subarchs used their own workaround (SIGH!) which got lost in > the conversion. >=20 > Now instead of fixing the underlying core code problem, Marcs patch > tried to work around the core code issue by increasing the minimal > tick delta at clockevents registration time so the resulting limit in > the core code backwards conversion did not violate the hardware > limits. More SIGH! It was not easy getting your attention with this problem :) Marc --=20 Pengutronix e.K. | Marc Kleine-Budde | Industrial Linux Solutions | Phone: +49-231-2826-924 | Vertretung West/Dortmund | Fax: +49-5121-206917-5555 | Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de | --lXvI9XfF7mgXCgDbuVn0cQiKUs2rrQQ7E Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.14 (GNU/Linux) Comment: Using GnuPG with Icedove - http://www.enigmail.net/ iEYEARECAAYFAlI41r4ACgkQjTAFq1RaXHPzFACeNit+gHlSELWSMdSOnu3lKCQU YbwAnjjdVI2CSJEWKFCAj6qf3ZHDoP8V =/iZ5 -----END PGP SIGNATURE----- --lXvI9XfF7mgXCgDbuVn0cQiKUs2rrQQ7E-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/