linux-kernel - [PATCH v4 08/11] clk: sunxi-ng: nkm: Support finding closest rate

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Message-Id: <20230717-pll-mipi_set_rate_parent-v4-8-04acf1d39765@oltmanns.dev>
Date:   Mon, 17 Jul 2023 15:34:32 +0200
From:   Frank Oltmanns <frank@...manns.dev>
To:     Maxime Ripard <mripard@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Samuel Holland <samuel@...lland.org>,
        Andre Przywara <andre.przywara@....com>,
        Roman Beranek <me@...y.cz>
Cc:     linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-sunxi@...ts.linux.dev, linux-kernel@...r.kernel.org,
        Frank Oltmanns <frank@...manns.dev>
Subject: [PATCH v4 08/11] clk: sunxi-ng: nkm: Support finding closest rate

When finding the best rate for a NKM clock, consider rates that are
higher than the requested rate, if the CCU_FEATURE_CLOSEST_RATE flag is
set by using the helper function ccu_is_better_rate().

Accommodate ccu_mux_helper_determine_rate to this change.

Signed-off-by: Frank Oltmanns <frank@...manns.dev>
---
 drivers/clk/sunxi-ng/ccu_mux.c |  2 +-
 drivers/clk/sunxi-ng/ccu_nkm.c | 18 ++++++++----------
 2 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/drivers/clk/sunxi-ng/ccu_mux.c b/drivers/clk/sunxi-ng/ccu_mux.c
index 1d557e323169..3ca695439620 100644
--- a/drivers/clk/sunxi-ng/ccu_mux.c
+++ b/drivers/clk/sunxi-ng/ccu_mux.c
@@ -139,7 +139,7 @@ int ccu_mux_helper_determine_rate(struct ccu_common *common,
 			goto out;
 		}
 
-		if ((req->rate - tmp_rate) < (req->rate - best_rate)) {
+		if (ccu_is_better_rate(common, req->rate, tmp_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 793160bc2d47..5439b9351cd7 100644
--- a/drivers/clk/sunxi-ng/ccu_nkm.c
+++ b/drivers/clk/sunxi-ng/ccu_nkm.c
@@ -39,6 +39,7 @@ static unsigned long ccu_nkm_optimal_parent_rate(unsigned long rate, unsigned lo
 }
 
 static unsigned long ccu_nkm_find_best_with_parent_adj(struct clk_hw *phw, struct _ccu_nkm *nkm,
+						       struct ccu_common *common,
 						       unsigned long *parent, unsigned long rate)
 {
 	unsigned long best_rate = 0, best_parent_rate = *parent, tmp_parent = *parent;
@@ -54,10 +55,8 @@ static unsigned long ccu_nkm_find_best_with_parent_adj(struct clk_hw *phw, struc
 				tmp_parent = clk_hw_round_rate(phw, tmp_parent);
 
 				tmp_rate = tmp_parent * _n * _k / _m;
-				if (tmp_rate > rate)
-					continue;
 
-				if ((rate - tmp_rate) < (rate - best_rate)) {
+				if (ccu_is_better_rate(common, rate, tmp_rate, best_rate)) {
 					best_rate = tmp_rate;
 					best_parent_rate = tmp_parent;
 					best_n = _n;
@@ -78,7 +77,7 @@ static unsigned long ccu_nkm_find_best_with_parent_adj(struct clk_hw *phw, struc
 }
 
 static unsigned long ccu_nkm_find_best(unsigned long parent, unsigned long rate,
-				       struct _ccu_nkm *nkm)
+				       struct _ccu_nkm *nkm, struct ccu_common *common)
 {
 	unsigned long best_rate = 0;
 	unsigned long best_n = 0, best_k = 0, best_m = 0;
@@ -91,9 +90,7 @@ static unsigned long ccu_nkm_find_best(unsigned long parent, unsigned long rate,
 
 				tmp_rate = parent * _n * _k / _m;
 
-				if (tmp_rate > rate)
-					continue;
-				if ((rate - tmp_rate) < (rate - best_rate)) {
+				if (ccu_is_better_rate(common, rate, tmp_rate, best_rate)) {
 					best_rate = tmp_rate;
 					best_n = _n;
 					best_k = _k;
@@ -186,9 +183,10 @@ static unsigned long ccu_nkm_round_rate(struct ccu_mux_internal *mux,
 		rate *= nkm->fixed_post_div;
 
 	if (!clk_hw_can_set_rate_parent(&nkm->common.hw))
-		rate = ccu_nkm_find_best(*parent_rate, rate, &_nkm);
+		rate = ccu_nkm_find_best(*parent_rate, rate, &_nkm, &nkm->common);
 	else
-		rate = ccu_nkm_find_best_with_parent_adj(parent_hw, &_nkm, parent_rate, rate);
+		rate = ccu_nkm_find_best_with_parent_adj(parent_hw, &_nkm, &nkm->common,
+							 parent_rate, rate);
 
 	if (nkm->common.features & CCU_FEATURE_FIXED_POSTDIV)
 		rate /= nkm->fixed_post_div;
@@ -223,7 +221,7 @@ static int ccu_nkm_set_rate(struct clk_hw *hw, unsigned long rate,
 	_nkm.min_m = 1;
 	_nkm.max_m = nkm->m.max ?: 1 << nkm->m.width;
 
-	ccu_nkm_find_best(parent_rate, rate, &_nkm);
+	ccu_nkm_find_best(parent_rate, rate, &_nkm, &nkm->common);
 
 	spin_lock_irqsave(nkm->common.lock, flags);
 

-- 
2.41.0