From mboxrd@z Thu Jan 1 00:00:00 1970 From: aisheng.dong@nxp.com (Dong Aisheng) Date: Wed, 8 Jun 2016 22:33:31 +0800 Subject: [PATCH 02/11] clk: imx: correct AV PLL rate formula In-Reply-To: <1465396420-27064-1-git-send-email-aisheng.dong@nxp.com> References: <1465396420-27064-1-git-send-email-aisheng.dong@nxp.com> Message-ID: <1465396420-27064-2-git-send-email-aisheng.dong@nxp.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org From: Anson Huang The audio/video PLL's rate calculation is as below in RM: Fref * (DIV_SELECT + NUM / DENOM), in origin 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 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 overflow a 32 bit value, 64 bit value should be used. After updating this formula, the dram PLL's rate is 1066MHz, which is correct, while the old formula gets 1056MHz. [Aisheng: fix clk_pllv3_av_round_rate too] Signed-off-by: Anson Huang Signed-off-by: Dong Aisheng --- drivers/clk/imx/clk-pllv3.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/clk/imx/clk-pllv3.c b/drivers/clk/imx/clk-pllv3.c index 44d294a336f0..eea2b1b3791e 100644 --- a/drivers/clk/imx/clk-pllv3.c +++ b/drivers/clk/imx/clk-pllv3.c @@ -218,8 +218,12 @@ 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 = (u64)parent_rate; - return (parent_rate * div) + ((parent_rate / mfd) * mfn); + temp64 *= mfn; + do_div(temp64, mfd); + + return (parent_rate * div) + (u32)temp64; } static long clk_pllv3_av_round_rate(struct clk_hw *hw, unsigned long rate, @@ -243,7 +247,7 @@ static long clk_pllv3_av_round_rate(struct clk_hw *hw, unsigned long rate, do_div(temp64, parent_rate); mfn = temp64; - return parent_rate * div + parent_rate / mfd * mfn; + return parent_rate * div + parent_rate * mfn / mfd; } static int clk_pllv3_av_set_rate(struct clk_hw *hw, unsigned long rate, -- 1.9.1