Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751336Ab1BVF0I (ORCPT ); Tue, 22 Feb 2011 00:26:08 -0500 Received: from mail-fx0-f46.google.com ([209.85.161.46]:51820 "EHLO mail-fx0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751060Ab1BVF0G convert rfc822-to-8bit (ORCPT ); Tue, 22 Feb 2011 00:26:06 -0500 MIME-Version: 1.0 X-Originating-IP: [173.13.129.225] In-Reply-To: <1298342392-21236-3-git-send-email-ccross@android.com> References: <1298342392-21236-1-git-send-email-ccross@android.com> <1298342392-21236-3-git-send-email-ccross@android.com> Date: Mon, 21 Feb 2011 21:26:04 -0800 Message-ID: Subject: Re: [PATCH 2/7] ARM: tegra: clock: Round rate before setting rate From: Olof Johansson To: Colin Cross Cc: linux-tegra@vger.kernel.org, konkers@android.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, mike@compulab.co.il, Russell King Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1320 Lines: 28 On Mon, Feb 21, 2011 at 6:39 PM, Colin Cross wrote: > Call the clock's round_rate op, if it exists, before calling > the set_rate op. ?This will help later when dvfs is added, > dvfs needs to know what the final rate will be before the > frequency changes. > > Also requires fixes to the round rate functions to ensure > calling round rate and then set rate will not cause the > frequency to be rounded down twice. ?When picking clock > divider values, the clock framework picks the closest > frequency that is lower than the requested frequency. ?If > the new frequency calculated from the divider value is > rounded down, and then passed to set_rate, it will get > rounded down again, possibly resulting in a frequency two > steps lower than the original requested frequency. > > Fix the problem by rounding up when calculating the frequency > coming out of a clock divider, so if that frequency is > requested again, the same divider value will be picked. > > Signed-off-by: Colin Cross Acked-by: Olof Johansson -- 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/