From mboxrd@z Thu Jan 1 00:00:00 1970 From: b20788@freescale.com (Anson Huang) Date: Fri, 24 Apr 2015 01:34:15 +0800 Subject: [PATCH] ARM: imx: correct Audio/Video PLL rate calculation formula Message-ID: <1429810455-22447-1-git-send-email-b20788@freescale.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org The audio/video PLL's rate calculation formula is as below in RM: Fref * (DIV_SELECT + NUM / DENOM), in original clk-pllv3's code, below code is used: (parent_rate * div) + ((parent_rate / mfd) * mfn as it does NOT consider the float data using div, so below calculation formula should be used as a decent method: (parent_rate * div) + ((parent_rate * mfn) / mfd) and we also need to consider parent_rate * mfd may exceed a 32 bit value, 64 bit value should be used. Signed-off-by: Anson Huang --- arch/arm/mach-imx/clk-pllv3.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/arm/mach-imx/clk-pllv3.c b/arch/arm/mach-imx/clk-pllv3.c index 641ebc5..f83cf0d 100644 --- a/arch/arm/mach-imx/clk-pllv3.c +++ b/arch/arm/mach-imx/clk-pllv3.c @@ -203,8 +203,12 @@ static unsigned long clk_pllv3_av_recalc_rate(struct clk_hw *hw, u32 mfn = readl_relaxed(pll->base + PLL_NUM_OFFSET); u32 mfd = readl_relaxed(pll->base + PLL_DENOM_OFFSET); u32 div = readl_relaxed(pll->base) & pll->div_mask; + u64 temp64 = parent_rate; - return (parent_rate * div) + ((parent_rate / mfd) * mfn); + temp64 *= mfn; + do_div(temp64, mfd); + + return (parent_rate * div) + temp64; } static long clk_pllv3_av_round_rate(struct clk_hw *hw, unsigned long rate, -- 1.9.1