From patchwork Mon May 29 13:34:33 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Frank Oltmanns X-Patchwork-Id: 13258599 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 365D7C77B7E for ; Mon, 29 May 2023 13:35:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229753AbjE2NfH (ORCPT ); Mon, 29 May 2023 09:35:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54560 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229601AbjE2NfG (ORCPT ); Mon, 29 May 2023 09:35:06 -0400 Received: from mout-p-102.mailbox.org (mout-p-102.mailbox.org [80.241.56.152]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0CA1F90; Mon, 29 May 2023 06:35:03 -0700 (PDT) Received: from smtp2.mailbox.org (smtp2.mailbox.org [10.196.197.2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-384) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mout-p-102.mailbox.org (Postfix) with ESMTPS id 4QVGjW6BrQz9slB; Mon, 29 May 2023 15:34:55 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oltmanns.dev; s=MBO0001; t=1685367295; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=embt6Ls9k2VANJwMs4RIikcIM5ejyhPH8j4QEL/1Chc=; b=pr9UbGDU54G0Xsls/ofB+w5J0fzZb/9S0Um4muqDszOKa1qBqPlPGQiWADhuDz+D0NVbxZ qY9udn/s6sy1N5b/rZN6OQXtu/S5ME2jEhO3SlPx9+lZ3ikiXPCs/eE9m4IY+BTLBTGZzt ziVsW2w3LV2crmzS21t+/JZYcYQH9hVCWSAyGzAGrJ12maXwajgNo4AJKmIqz33+TEw40L wSbuFn4/P6DJeN50rJmPgja+mVnq82y/NLzLnPkbjhe9A1wcUrUoP5oUuY1+Vi3WlCPWSN /0DS+bz2w7Q0C2KNKkHCQy2vcUlwec/yfVsBeBJD7MIWE8DpAwEIqqjhXMJo2A== From: Frank Oltmanns To: Michael Turquette , Stephen Boyd Cc: Frank Oltmanns , Abel Vesa , Peng Fan , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , NXP Linux Team , Jacky Bai , Anson Huang , linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH] clk: fractional-divider: Improve approximation when zero based Date: Mon, 29 May 2023 15:34:33 +0200 Message-Id: <20230529133433.56215-1-frank@oltmanns.dev> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-clk@vger.kernel.org Consider the CLK_FRAC_DIVIDER_ZERO_BASED flag when finding the best approximation for m and n. By doing so, increase the range of valid values for the numerator and denominator by 1. Cc: A.s. Dong --- I stumpled upon this, when familiarizing myself with clk drivers. Unfortunately, I have no boards to test this patch. It seems the only user of this flag in mainline is drivers/clk/imx/clk-composite-7ulp.c, therefore I'm cc-ing get_maintainers.pl --git-blame -f drivers/clk/imx/clk-composite-7ulp.c in the hopes of a wider audience. Thank you for considering this contribution, Frank drivers/clk/clk-fractional-divider.c | 26 +++++++++++++++++++------- 1 file changed, 19 insertions(+), 7 deletions(-) diff --git a/drivers/clk/clk-fractional-divider.c b/drivers/clk/clk-fractional-divider.c index 479297763e70..7da21cd2bdb1 100644 --- a/drivers/clk/clk-fractional-divider.c +++ b/drivers/clk/clk-fractional-divider.c @@ -123,6 +123,7 @@ void clk_fractional_divider_general_approximation(struct clk_hw *hw, unsigned long *m, unsigned long *n) { struct clk_fractional_divider *fd = to_clk_fd(hw); + unsigned long max_m, max_n; /* * Get rate closer to *parent_rate to guarantee there is no overflow @@ -138,9 +139,15 @@ void clk_fractional_divider_general_approximation(struct clk_hw *hw, rate <<= scale - fd->nwidth; } - rational_best_approximation(rate, *parent_rate, - GENMASK(fd->mwidth - 1, 0), GENMASK(fd->nwidth - 1, 0), - m, n); + if (fd->flags & CLK_FRAC_DIVIDER_ZERO_BASED) { + max_m = 1 << fd->mwidth; + max_n = 1 << fd->nwidth; + } else { + max_m = GENMASK(fd->mwidth - 1, 0); + max_n = GENMASK(fd->nwidth - 1, 0); + } + + rational_best_approximation(rate, *parent_rate, max_m, max_n, m, n); } static long clk_fd_round_rate(struct clk_hw *hw, unsigned long rate, @@ -169,13 +176,18 @@ static int clk_fd_set_rate(struct clk_hw *hw, unsigned long rate, { struct clk_fractional_divider *fd = to_clk_fd(hw); unsigned long flags = 0; - unsigned long m, n; + unsigned long m, n, max_m, max_n; u32 mmask, nmask; u32 val; - rational_best_approximation(rate, parent_rate, - GENMASK(fd->mwidth - 1, 0), GENMASK(fd->nwidth - 1, 0), - &m, &n); + if (fd->flags & CLK_FRAC_DIVIDER_ZERO_BASED) { + max_m = 1 << fd->mwidth; + max_n = 1 << fd->nwidth; + } else { + max_m = GENMASK(fd->mwidth - 1, 0); + max_n = GENMASK(fd->nwidth - 1, 0); + } + rational_best_approximation(rate, parent_rate, max_m, max_n, &m, &n); if (fd->flags & CLK_FRAC_DIVIDER_ZERO_BASED) { m--;