From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CDA05C636CA for ; Fri, 16 Jul 2021 13:34:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B098561260 for ; Fri, 16 Jul 2021 13:34:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240079AbhGPNh1 (ORCPT ); Fri, 16 Jul 2021 09:37:27 -0400 Received: from mga18.intel.com ([134.134.136.126]:56332 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239999AbhGPNhX (ORCPT ); Fri, 16 Jul 2021 09:37:23 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10046"; a="197993395" X-IronPort-AV: E=Sophos;i="5.84,245,1620716400"; d="scan'208";a="197993395" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Jul 2021 06:34:26 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.84,245,1620716400"; d="scan'208";a="574019903" Received: from black.fi.intel.com ([10.237.72.28]) by fmsmga001.fm.intel.com with ESMTP; 16 Jul 2021 06:34:23 -0700 Received: by black.fi.intel.com (Postfix, from userid 1003) id 459A7B9; Fri, 16 Jul 2021 16:34:51 +0300 (EEST) From: Andy Shevchenko To: Andy Shevchenko , Heiko Stuebner , Elaine Zhang , Stephen Boyd , linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org Cc: Michael Turquette , Liu Ying Subject: [PATCH v2 2/3] clk: fractional-divider: Introduce NO_PRESCALER flag Date: Fri, 16 Jul 2021 16:34:47 +0300 Message-Id: <20210716133448.24890-2-andriy.shevchenko@linux.intel.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210716133448.24890-1-andriy.shevchenko@linux.intel.com> References: <20210716133448.24890-1-andriy.shevchenko@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The newly introduced flag, when set, makes the flow to skip the assumption that the caller will use an additional 2^scale prescaler to get the desired clock rate. Reported-by: Liu Ying Signed-off-by: Andy Shevchenko --- v2: moved entire snipped under new flag check (Liu) drivers/clk/clk-fractional-divider.c | 10 ++++++---- include/linux/clk-provider.h | 5 +++++ 2 files changed, 11 insertions(+), 4 deletions(-) diff --git a/drivers/clk/clk-fractional-divider.c b/drivers/clk/clk-fractional-divider.c index 535d299af646..5f4b6a8aef67 100644 --- a/drivers/clk/clk-fractional-divider.c +++ b/drivers/clk/clk-fractional-divider.c @@ -76,16 +76,18 @@ 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 scale; /* * Get rate closer to *parent_rate to guarantee there is no overflow * for m and n. In the result it will be the nearest rate left shifted * by (scale - fd->nwidth) bits. */ - scale = fls_long(*parent_rate / rate - 1); - if (scale > fd->nwidth) - rate <<= scale - fd->nwidth; + if (!(fd->flags & CLK_FRAC_DIVIDER_NO_PRESCALER)) { + unsigned long scale = fls_long(*parent_rate / rate - 1); + + if (scale > fd->nwidth) + rate <<= scale - fd->nwidth; + } rational_best_approximation(rate, *parent_rate, GENMASK(fd->mwidth - 1, 0), GENMASK(fd->nwidth - 1, 0), diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h index d83b829305c0..f74d0afe275f 100644 --- a/include/linux/clk-provider.h +++ b/include/linux/clk-provider.h @@ -1001,6 +1001,10 @@ struct clk_hw *devm_clk_hw_register_fixed_factor(struct device *dev, * CLK_FRAC_DIVIDER_BIG_ENDIAN - By default little endian register accesses are * used for the divider register. Setting this flag makes the register * accesses big endian. + * CLK_FRAC_DIVIDER_NO_PRESCALER - By default the resulting rate may be shifted + * left by a few bits in case when the asked one is quite small to satisfy + * the desired range of denominator. If the caller wants to get the best + * rate without using an additional prescaler, this flag may be set. */ struct clk_fractional_divider { struct clk_hw hw; @@ -1022,6 +1026,7 @@ struct clk_fractional_divider { #define CLK_FRAC_DIVIDER_ZERO_BASED BIT(0) #define CLK_FRAC_DIVIDER_BIG_ENDIAN BIT(1) +#define CLK_FRAC_DIVIDER_NO_PRESCALER BIT(2) extern const struct clk_ops clk_fractional_divider_ops; struct clk *clk_register_fractional_divider(struct device *dev, -- 2.30.2