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

Shawn Guo
2016-06-12T11:31:08Z

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.