linux-kernel - [PATCH 4.14 034/186] clk: bcm-2835: Pick the closest clock rate

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Message-Id: <20220124183938.221804577@linuxfoundation.org>
Date:   Mon, 24 Jan 2022 19:41:49 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Maxime Ripard <maxime@...no.tech>,
        Stephen Boyd <sboyd@...nel.org>,
        Nicolas Saenz Julienne <nsaenz@...nel.org>,
        Michael Stapelberg <michael@...pelberg.ch>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.14 034/186] clk: bcm-2835: Pick the closest clock rate

From: Maxime Ripard <maxime@...no.tech>

[ Upstream commit 5517357a4733d7cf7c17fc79d0530cfa47add372 ]

The driver currently tries to pick the closest rate that is lower than
the rate being requested.

This causes an issue with clk_set_min_rate() since it actively checks
for the rounded rate to be above the minimum that was just set.

Let's change the logic a bit to pick the closest rate to the requested
rate, no matter if it's actually higher or lower.

Fixes: 6d18b8adbe67 ("clk: bcm2835: Support for clock parent selection")
Signed-off-by: Maxime Ripard <maxime@...no.tech>
Acked-by: Stephen Boyd <sboyd@...nel.org>
Reviewed-by: Nicolas Saenz Julienne <nsaenz@...nel.org>
Tested-by: Nicolas Saenz Julienne <nsaenz@...nel.org> # boot and basic functionality
Tested-by: Michael Stapelberg <michael@...pelberg.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210922125419.4125779-2-maxime@cerno.tech
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/clk/bcm/clk-bcm2835.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c
index 98295b9703178..d6cd1cc3f8e4d 100644
--- a/drivers/clk/bcm/clk-bcm2835.c
+++ b/drivers/clk/bcm/clk-bcm2835.c
@@ -1233,7 +1233,7 @@ static int bcm2835_clock_determine_rate(struct clk_hw *hw,
 		rate = bcm2835_clock_choose_div_and_prate(hw, i, req->rate,
 							  &div, &prate,
 							  &avgrate);
-		if (rate > best_rate && rate <= req->rate) {
+		if (abs(req->rate - rate) < abs(req->rate - best_rate)) {
 			best_parent = parent;
 			best_prate = prate;
 			best_rate = rate;
-- 
2.34.1