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Re: [PATCH 02/11] clk: imx: correct AV PLL rate formula

From	Shawn Guo <shawnguo@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH 02/11] clk: imx: correct AV PLL rate formula
Date	2016-06-12 13:40 +0200
Message-ID	<rJbUd-854-19@gated-at.bofh.it> (permalink)
References	<rI2SZ-3kN-9@gated-at.bofh.it> <rJbUd-854-21@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Wed, Jun 08, 2016 at 10:33:31PM +0800, Dong Aisheng wrote:
> From: Anson Huang <b20788@freescale.com>
> 
> 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 <b20788@freescale.com>
> Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>

Applied, thanks.

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Re: [PATCH 02/11] clk: imx: correct AV PLL rate formula Shawn Guo <shawnguo@kernel.org> - 2016-06-12 13:40 +0200

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