From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1ZG75X-0002WR-8c for barebox@lists.infradead.org; Fri, 17 Jul 2015 14:58:11 +0000 Message-ID: <1437145068.3498.117.camel@pengutronix.de> From: Jan =?ISO-8859-1?Q?L=FCbbe?= Date: Fri, 17 Jul 2015 16:57:48 +0200 In-Reply-To: <1437140350-14352-1-git-send-email-d.schultz@phytec.de> References: <1437140350-14352-1-git-send-email-d.schultz@phytec.de> Mime-Version: 1.0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: Re: [PATCH v3 2/2] ARM: am335x: Changed timer To: Daniel Schultz Cc: barebox@lists.infradead.org On Fr, 2015-07-17 at 15:39 +0200, Daniel Schultz wrote: > The dmtimer0 is too inaccurate to be used for measurements. > We switch to the more accurate dmtimer2. Ah, OK, after looking at the TRM again, the real reason for the inaccuracy seems to be that the 32KiHz for dmtimer0 is *not* derived from the RTC crystal, but from an internal RC oscillator. The kernel uses dmtimer1 for the clocksource by switching it to the M_OSC in the PRCM. The dmtimer2 is used for clockevents and runs from M_OSC by default. While we could set the dmtimer1 source to M_OSC in the clock setup, it seems simpler to just use dmtimer2. The commit message should explain the reasoning behind the switch. Regards, Jan -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox