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From: Chen-Yu Tsai <wens@kernel.org>
To: Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Stephen Boyd <sboyd@kernel.org>, Chen-Yu Tsai <wens@csie.org>,
	Jernej Skrabec <jernej@kernel.org>,
	Samuel Holland <samuel@sholland.org>
Cc: Andre Przywara <andre.przywara@arm.com>,
	linux-sunxi@lists.linux.dev, linux-clk@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH 3/8] clk: sunxi-ng: mp: Fix dual-divider clock rate readback
Date: Sun, 31 Aug 2025 01:08:56 +0800	[thread overview]
Message-ID: <20250830170901.1996227-4-wens@kernel.org> (raw)
In-Reply-To: <20250830170901.1996227-1-wens@kernel.org>

From: Chen-Yu Tsai <wens@csie.org>

When dual-divider clock support was introduced, the P divider offset was
left out of the .recalc_rate readback function. This causes the clock
rate to become bogus or even zero (possibly due to the P divider being
1, leading to a divide-by-zero).

Fix this by incorporating the P divider offset into the calculation.

Fixes: 45717804b75e ("clk: sunxi-ng: mp: introduce dual-divider clock")
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
---
 drivers/clk/sunxi-ng/ccu_mp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clk/sunxi-ng/ccu_mp.c b/drivers/clk/sunxi-ng/ccu_mp.c
index 354c981943b6..4221b1888b38 100644
--- a/drivers/clk/sunxi-ng/ccu_mp.c
+++ b/drivers/clk/sunxi-ng/ccu_mp.c
@@ -185,7 +185,7 @@ static unsigned long ccu_mp_recalc_rate(struct clk_hw *hw,
 	p &= (1 << cmp->p.width) - 1;
 
 	if (cmp->common.features & CCU_FEATURE_DUAL_DIV)
-		rate = (parent_rate / p) / m;
+		rate = (parent_rate / (p + cmp->p.offset)) / m;
 	else
 		rate = (parent_rate >> p) / m;
 
-- 
2.39.5



  parent reply	other threads:[~2025-08-30 17:31 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-08-30 17:08 [PATCH 0/8] arm64: allwinner: a523: Enable MCU PRCM and NPU Chen-Yu Tsai
2025-08-30 17:08 ` [PATCH 1/8] dt-bindings: clock: sun55i-a523-ccu: Add missing NPU module clock Chen-Yu Tsai
2025-09-01 21:29   ` Rob Herring (Arm)
2025-08-30 17:08 ` [PATCH 2/8] dt-bindings: clock: sun55i-a523-ccu: Add A523 MCU CCU clock controller Chen-Yu Tsai
2025-09-01 21:31   ` Rob Herring (Arm)
2025-08-30 17:08 ` Chen-Yu Tsai [this message]
2025-08-30 17:08 ` [PATCH 4/8] clk: sunxi-ng: sun55i-a523-ccu: Add missing NPU module clock Chen-Yu Tsai
2025-08-30 17:08 ` [PATCH 5/8] clk: sunxi-ng: div: support power-of-two dividers Chen-Yu Tsai
2025-08-30 17:08 ` [PATCH 6/8] clk: sunxi-ng: add support for the A523/T527 MCU CCU Chen-Yu Tsai
2025-08-30 17:09 ` [PATCH 7/8] arm64: dts: allwinner: a523: Add MCU PRCM CCU node Chen-Yu Tsai
2025-08-30 17:09 ` [PATCH 8/8] arm64: dts: allwinner: a523: Add NPU device node Chen-Yu Tsai

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