From patchwork Tue Jul 25 07:37:02 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Quentin Schulz X-Patchwork-Id: 9861283 X-Patchwork-Delegate: sboyd@codeaurora.org Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 059D2601A1 for ; Tue, 25 Jul 2017 07:41:09 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id EB9DA283ED for ; Tue, 25 Jul 2017 07:41:08 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id E0173285FB; Tue, 25 Jul 2017 07:41:08 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 674FB283ED for ; Tue, 25 Jul 2017 07:41:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750922AbdGYHlH (ORCPT ); Tue, 25 Jul 2017 03:41:07 -0400 Received: from mail.free-electrons.com ([62.4.15.54]:42283 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750857AbdGYHlF (ORCPT ); Tue, 25 Jul 2017 03:41:05 -0400 Received: by mail.free-electrons.com (Postfix, from userid 110) id A24D821E7F; Tue, 25 Jul 2017 09:41:02 +0200 (CEST) Received: from localhost.localdomain (LStLambert-657-1-97-87.w90-63.abo.wanadoo.fr [90.63.216.87]) by mail.free-electrons.com (Postfix) with ESMTPSA id 3650E208E2; Tue, 25 Jul 2017 09:40:52 +0200 (CEST) From: Quentin Schulz To: mturquette@baylibre.com, sboyd@codeaurora.org, robh+dt@kernel.org, mark.rutland@arm.com, lgirdwood@gmail.com, broonie@kernel.org, nicolas.ferre@microchip.com, alexandre.belloni@free-electrons.com, linux@armlinux.org.uk, boris.brezillon@free-electrons.com, perex@perex.cz, tiwai@suse.com Cc: cyrille.pitchen@wedev4u.fr, thomas.petazzoni@free-electrons.com, linux-clk@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, alsa-devel@alsa-project.org, linux-arm-kernel@lists.infradead.org, Quentin Schulz Subject: [PATCH v4 1/9] clk: at91: clk-generated: remove useless divisor loop Date: Tue, 25 Jul 2017 09:37:02 +0200 Message-Id: X-Mailer: git-send-email 2.11.0 In-Reply-To: References: In-Reply-To: References: Sender: linux-clk-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-clk@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The driver requests the current clk rate of each of its parent clocks to decide whether a clock rate is suitable or not. It does not request determine_rate from a parent clock which could request a rate change in parent clock (i.e. there is no parent rate propagation). We know the rate we want (passed along req argument of the function) and the parent clock rate, thus we know the closest rounded divisor, we don't need to iterate over the available divisors to find the best one for a given clock. Signed-off-by: Quentin Schulz Acked-by: Boris Brezillon Acked-by: Nicolas Ferre --- drivers/clk/at91/clk-generated.c | 25 ++++++++++++------------- 1 file changed, 12 insertions(+), 13 deletions(-) diff --git a/drivers/clk/at91/clk-generated.c b/drivers/clk/at91/clk-generated.c index f0b7ae9..ef4b4e0 100644 --- a/drivers/clk/at91/clk-generated.c +++ b/drivers/clk/at91/clk-generated.c @@ -124,19 +124,18 @@ static int clk_generated_determine_rate(struct clk_hw *hw, (gck->range.max && min_rate > gck->range.max)) continue; - for (div = 1; div < GENERATED_MAX_DIV + 2; div++) { - tmp_rate = DIV_ROUND_CLOSEST(parent_rate, div); - tmp_diff = abs(req->rate - tmp_rate); - - if (best_diff < 0 || best_diff > tmp_diff) { - best_rate = tmp_rate; - best_diff = tmp_diff; - req->best_parent_rate = parent_rate; - req->best_parent_hw = parent; - } - - if (!best_diff || tmp_rate < req->rate) - break; + div = DIV_ROUND_CLOSEST(parent_rate, req->rate); + if (!div) + tmp_rate = parent_rate; + else + tmp_rate = parent_rate / div; + tmp_diff = abs(req->rate - tmp_rate); + + if (best_diff < 0 || best_diff > tmp_diff) { + best_rate = tmp_rate; + best_diff = tmp_diff; + req->best_parent_rate = parent_rate; + req->best_parent_hw = parent; } if (!best_diff)