From mboxrd@z Thu Jan 1 00:00:00 1970 From: mkl@pengutronix.de (Marc Kleine-Budde) Date: Wed, 18 Sep 2013 00:25:02 +0200 Subject: [PATCH] clockevents: Sanitize ticks to nsec conversion In-Reply-To: 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> Message-ID: <5238D6BE.6040603@pengutronix.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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. > > 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. > > 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 -- 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 | -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 259 bytes Desc: OpenPGP digital signature URL: