From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mout-p-101.mailbox.org (mout-p-101.mailbox.org [80.241.56.151]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 36F1A20EB for ; Sat, 27 May 2023 13:36:30 +0000 (UTC) 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-101.mailbox.org (Postfix) with ESMTPS id 4QT2fl1DKwz9sZf; Sat, 27 May 2023 15:28:15 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oltmanns.dev; s=MBO0001; t=1685194095; 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: in-reply-to:in-reply-to:references:references; bh=xCkY+0YMty2Tdhd1Y9tZlY6x9qv5DdKhwiRQK/bh6ws=; b=n9z6hRYncmjSRlIQD8fqKNMxq0KursHy0vY+TFGAvJ8y5Kcpc23vtkcWrFLxhMp2C7Lv9T fIcMrB6u+BgipYwZZ+IVs+BA9hQ0roYoPen0O6wF6PNr6kvnKc9plVIOpG9ES95mPxVUhu RocJ+vPjb1+ErdiWC30xE5PTwm/eh4Kmt4evEI2o1iBEhC1N5s4xhD0Ji5hUT9NwHF4sAW Yc34+lvSJv+Wm328W1Fz3Hyu6bNhHV3cMx9YFsONS7/sNga0Y0M9taBihJ5s31yIZC+Aek 5TtOi5UqZYs5fPitBGk2kVpswN8zsztIOPjaO1eIugzsv/tGgAYmuCK69YIj7g== From: Frank Oltmanns To: linux-arm-kernel@lists.infradead.org, linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org, linux-sunxi@lists.linux.dev Cc: Frank Oltmanns , Andre Przywara , Chen-Yu Tsai , Icenowy Zheng , Jernej Skrabec , Maxime Ripard , Michael Turquette , Rob Herring , Samuel Holland , Stephen Boyd Subject: [RFC PATCH 1/3] clk: sunxi-ng: nkm: Minimize difference when finding rate Date: Sat, 27 May 2023 15:27:45 +0200 Message-Id: <20230527132747.83196-2-frank@oltmanns.dev> In-Reply-To: <20230527132747.83196-1-frank@oltmanns.dev> References: <20230527132747.83196-1-frank@oltmanns.dev> Precedence: bulk X-Mailing-List: linux-sunxi@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Instead of selecting the first rate that is less than the requested rate, select the rate that minimizes the absolute difference with the requested rate. This ensures a more accurate rate selection, when the closest available rate is higher than the requested rate. Also stop searching once an exact match is found. Adjust mux to this change in rate selection. Signed-off-by: Frank Oltmanns --- drivers/clk/sunxi-ng/ccu_mux.c | 2 +- drivers/clk/sunxi-ng/ccu_nkm.c | 13 +++++++++---- 2 files changed, 10 insertions(+), 5 deletions(-) diff --git a/drivers/clk/sunxi-ng/ccu_mux.c b/drivers/clk/sunxi-ng/ccu_mux.c index 9303e1f02ffd..6fe0a8d098f1 100644 --- a/drivers/clk/sunxi-ng/ccu_mux.c +++ b/drivers/clk/sunxi-ng/ccu_mux.c @@ -145,7 +145,7 @@ int ccu_mux_helper_determine_rate(struct ccu_common *common, goto out; } - if ((req->rate - tmp_rate) < (req->rate - best_rate)) { + if (abs(req->rate - tmp_rate) < abs(req->rate - best_rate)) { best_rate = tmp_rate; best_parent_rate = parent_rate; best_parent = parent; diff --git a/drivers/clk/sunxi-ng/ccu_nkm.c b/drivers/clk/sunxi-ng/ccu_nkm.c index a0978a50edae..94d2a83992b2 100644 --- a/drivers/clk/sunxi-ng/ccu_nkm.c +++ b/drivers/clk/sunxi-ng/ccu_nkm.c @@ -19,7 +19,7 @@ struct _ccu_nkm { static unsigned long ccu_nkm_find_best(unsigned long parent, unsigned long rate, struct _ccu_nkm *nkm) { - unsigned long best_rate = 0; + unsigned long best_rate = 0, best_diff = ULONG_MAX; unsigned long best_n = 0, best_k = 0, best_m = 0; unsigned long _n, _k, _m; @@ -27,21 +27,26 @@ static unsigned long ccu_nkm_find_best(unsigned long parent, unsigned long rate, for (_n = nkm->min_n; _n <= nkm->max_n; _n++) { for (_m = nkm->min_m; _m <= nkm->max_m; _m++) { unsigned long tmp_rate; + unsigned long tmp_diff; tmp_rate = parent * _n * _k / _m; - if (tmp_rate > rate) - continue; - if ((rate - tmp_rate) < (rate - best_rate)) { + tmp_diff = abs(rate - tmp_rate); + + if (tmp_diff < best_diff) { best_rate = tmp_rate; + best_diff = tmp_diff; best_n = _n; best_k = _k; best_m = _m; + if (best_diff == 0) + goto out; } } } } +out: nkm->n = best_n; nkm->k = best_k; nkm->m = best_m; -- 2.40.1