From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mout-p-202.mailbox.org (mout-p-202.mailbox.org [80.241.56.172]) (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 E556D20EB for ; Sat, 27 May 2023 13:37:17 +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-202.mailbox.org (Postfix) with ESMTPS id 4QT2fp11vSz9scm; Sat, 27 May 2023 15:28:18 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oltmanns.dev; s=MBO0001; t=1685194098; 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=4E0//LKBNUllQfAtkiLIrhWN7vXYAzX6w6tTzQQg8xk=; b=OvGVuYsKY7RuRPhxEsjloD+qLuaq7awbeJKTP8VfsQmuXdzIo5jrdutG53X3Lo2nnc+rpG 76ZGsRemAnDeuwaChPtGROHGTOXlVweQHvkn03uIuBEguEACkXmNr7MzE+KmkYbrdnkJeY y30NivBAuv6lziTLewyWXYZprgOfcd0gwsXNTPf2LquA/K8NtM3YKv1luQ1cjJo2u8z/+y gNwhnCk70+EoQKHm853UIogoYSwytYF9+j7EUAO7qFab5WvI4t3CcG4G0c+SfXI88DycWo JtQeA69v9mbTY7igiAfe8A/hFN42x+8awJX66stHWJKYVDJ4ZIaFkQPjYlCviQ== 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 2/3] clk: sunxi-ng: Implement precalculated NKM rate selection Date: Sat, 27 May 2023 15:27:46 +0200 Message-Id: <20230527132747.83196-3-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 Add a new precalculation method for NKM clock rate selection in the sunxi-ng clock driver. Introduce ccu_nkm_find_best_precalc which uses a precalculated table of valid NKM combinations (struct clk_nkm_table and struct clk_nkm_combo) to find the best rate. This approach provides faster rate selection by searching a table of valid combinations rather than calculating for all possible combinations. The table of NKM combinations needs to be initialized with meaningful combinations only, i.e. removing redundant combinations that result in the same rate. Keep the existing ccu_nkm_find_best function in place and use it as a fallback if no precalculated table is provided. Signed-off-by: Frank Oltmanns --- drivers/clk/sunxi-ng/ccu_nkm.c | 84 +++++++++++++++++++++++++++------- drivers/clk/sunxi-ng/ccu_nkm.h | 26 +++++++++++ 2 files changed, 94 insertions(+), 16 deletions(-) diff --git a/drivers/clk/sunxi-ng/ccu_nkm.c b/drivers/clk/sunxi-ng/ccu_nkm.c index 94d2a83992b2..9652f6df17bd 100644 --- a/drivers/clk/sunxi-ng/ccu_nkm.c +++ b/drivers/clk/sunxi-ng/ccu_nkm.c @@ -54,6 +54,49 @@ static unsigned long ccu_nkm_find_best(unsigned long parent, unsigned long rate, return best_rate; } +static unsigned long ccu_nkm_find_best_precalc(unsigned long parent, + unsigned long rate, + struct _ccu_nkm *nkm, + struct clk_nkm_table *table) +{ + unsigned long best_rate = 0, best_diff = ULONG_MAX; + unsigned long best_n = 0, best_k = 0, best_m = 0; + int start = 0, end = table->num - 1, mid; + + while (start <= end) { + unsigned long tmp_rate; + unsigned long tmp_diff; + + mid = (start + end) / 2; + + tmp_rate = parent * table->combos[mid].n * table->combos[mid].k / + table->combos[mid].m; + + tmp_diff = abs(rate - tmp_rate); + + if (tmp_diff < best_diff) { + best_rate = tmp_rate; + best_diff = tmp_diff; + best_n = table->combos[mid].n; + best_k = table->combos[mid].k; + best_m = table->combos[mid].m; + if (best_diff == 0) + goto out; + } + if (rate < tmp_rate) + end = mid - 1; + else + start = mid + 1; + } + +out: + nkm->n = best_n; + nkm->k = best_k; + nkm->m = best_m; + + return best_rate; +} + static void ccu_nkm_disable(struct clk_hw *hw) { struct ccu_nkm *nkm = hw_to_ccu_nkm(hw); @@ -119,17 +162,22 @@ static unsigned long ccu_nkm_round_rate(struct ccu_mux_internal *mux, struct ccu_nkm *nkm = data; struct _ccu_nkm _nkm; - _nkm.min_n = nkm->n.min ?: 1; - _nkm.max_n = nkm->n.max ?: 1 << nkm->n.width; - _nkm.min_k = nkm->k.min ?: 1; - _nkm.max_k = nkm->k.max ?: 1 << nkm->k.width; - _nkm.min_m = 1; - _nkm.max_m = nkm->m.max ?: 1 << nkm->m.width; - if (nkm->common.features & CCU_FEATURE_FIXED_POSTDIV) rate *= nkm->fixed_post_div; - rate = ccu_nkm_find_best(*parent_rate, rate, &_nkm); + if (nkm->table.num) + rate = ccu_nkm_find_best_precalc(*parent_rate, rate, &_nkm, + &nkm->table); + else { + _nkm.min_n = nkm->n.min ?: 1; + _nkm.max_n = nkm->n.max ?: 1 << nkm->n.width; + _nkm.min_k = nkm->k.min ?: 1; + _nkm.max_k = nkm->k.max ?: 1 << nkm->k.width; + _nkm.min_m = 1; + _nkm.max_m = nkm->m.max ?: 1 << nkm->m.width; + + rate = ccu_nkm_find_best(*parent_rate, rate, &_nkm); + } if (nkm->common.features & CCU_FEATURE_FIXED_POSTDIV) rate /= nkm->fixed_post_div; @@ -157,14 +205,18 @@ static int ccu_nkm_set_rate(struct clk_hw *hw, unsigned long rate, if (nkm->common.features & CCU_FEATURE_FIXED_POSTDIV) rate *= nkm->fixed_post_div; - _nkm.min_n = nkm->n.min ?: 1; - _nkm.max_n = nkm->n.max ?: 1 << nkm->n.width; - _nkm.min_k = nkm->k.min ?: 1; - _nkm.max_k = nkm->k.max ?: 1 << nkm->k.width; - _nkm.min_m = 1; - _nkm.max_m = nkm->m.max ?: 1 << nkm->m.width; - - ccu_nkm_find_best(parent_rate, rate, &_nkm); + if (nkm->table.num) + rate = ccu_nkm_find_best_precalc(*parent_rate, rate, &_nkm, + &nkm->table); + else { + _nkm.min_n = nkm->n.min ?: 1; + _nkm.max_n = nkm->n.max ?: 1 << nkm->n.width; + _nkm.min_k = nkm->k.min ?: 1; + _nkm.max_k = nkm->k.max ?: 1 << nkm->k.width; + _nkm.min_m = 1; + _nkm.max_m = nkm->m.max ?: 1 << nkm->m.width; + ccu_nkm_find_best(parent_rate, rate, &_nkm); + } spin_lock_irqsave(nkm->common.lock, flags); diff --git a/drivers/clk/sunxi-ng/ccu_nkm.h b/drivers/clk/sunxi-ng/ccu_nkm.h index 6601defb3f38..fa5551724921 100644 --- a/drivers/clk/sunxi-ng/ccu_nkm.h +++ b/drivers/clk/sunxi-ng/ccu_nkm.h @@ -12,6 +12,30 @@ #include "ccu_div.h" #include "ccu_mult.h" +struct clk_nkm_combo { + u8 n; + u8 k; + u8 m; +}; + +/** + * struct clk_nkm_table - Table of all meaningful combinations for n, k, and m + * + * @num: Number of entries in the table + * @combos: Array of combos (of size num) that are supported by this clock. + * + * This table shall contain all meaningful combinations of n, k, and m. That + * means that combinations that result in the same clock rate shall only be + * listed once. For example, if both + * { .n = 1, .k = 2, .m = 2} and { .n = 2, .k = 2, .m = 4} + * are valid values for n, k, and m, only one of them would be allowed because + * both result in a factor of 1.0. + */ +struct clk_nkm_table { + size_t num; + struct clk_nkm_combo *combos; +}; + /* * struct ccu_nkm - Definition of an N-K-M clock * @@ -29,6 +53,8 @@ struct ccu_nkm { unsigned int fixed_post_div; struct ccu_common common; + + struct clk_nkm_table table; }; #define SUNXI_CCU_NKM_WITH_MUX_GATE_LOCK(_struct, _name, _parents, _reg, \ -- 2.40.1