Re: [PATCH] clk: rockchip: fix frac settings of GPLL clock for rk3328

From: Heiko Stuebner
Date: Mon Dec 24 2018 - 02:54:41 EST


Hi Elaine,

Am Montag, 24. Dezember 2018, 08:48:05 CET schrieb zhangqing@xxxxxxxxxxxxxx:
> Hi: Heiko:
>
> This explanation and the change is OK. Thanks for Katsuhiro's correction.

thanks for your quick confirmation. Can I make this an

Acked-by: Elaine Zhang <zhangqing@xxxxxxxxxxxxxx>

when applying the patch?

Thanks
Heiko


> åæ
> çåçèåçåèäæéåå
> Fuzhou Rockchip Electronics Co.,Ltd
> ååïçåççååéçèèäåé89åèäåAå21åæ
> Add:No.21 Building, A District, No.89 Software Boulevard Fuzhou, Fujian 350003, P.R.China
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> E-mail:elaine.zhang@xxxxxxxxxxxxxx
>
> From: Heiko Stuebner
> Date: 2018-12-24 15:34
> To: Katsuhiro Suzuki; Finley Xiao; Elaine Zhang
> CC: linux-rockchip; linux-arm-kernel; linux-kernel
> Subject: Re: [PATCH] clk: rockchip: fix frac settings of GPLL clock for rk3328
> Hi,
>
> Am Samstag, 22. Dezember 2018, 17:42:49 CET schrieb Katsuhiro Suzuki:
> > This patch fixes settings of GPLL frequency in fractional mode for
> > rk3328. In this mode, FOUTVCO is calcurated by following formula:
> > FOUTVCO = FREF * FBDIV / REFDIV + ((FREF * FRAC / REFDIV) >> 24)
> >
> > The problem is in FREF * FRAC >> 24 term. This result always lacks
> > one from target value is specified by rate member. For example first
> > itme of rk3328_pll_frac_rate originally has
> > - rate : 1016064000
> > - refdiv: 3
> > - fbdiv : 127
> > - frac : 134217
> > - FREF * FBDIV / REFDIV = 1016000000
> > - (FREF * FRAC / REFDIV) >> 24 = 63999
> > Thus calculated rate is 1016063999. It seems wrong.
> >
> > If frac has 134218 (it is increased 1 from original value), second
> > term is 64000. All other items have same situation. So this patch
> > adds 1 to frac member in all items of rk3328_pll_frac_rate.
> >
> > Signed-off-by: Katsuhiro Suzuki <katsuhiro@xxxxxxxxxxxxx>
>
> so while this sounds all quite right to me, I've added some Rockchip
> people that have clock experience to hopefully get an Ack on the
> change :-)
>
> @Elaine + Finley: does this explanation and the below change look right?
>
>
> Thanks
> Heiko
>
> > ---
> > drivers/clk/rockchip/clk-rk3328.c | 12 ++++++------
> > 1 file changed, 6 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/clk/rockchip/clk-rk3328.c b/drivers/clk/rockchip/clk-rk3328.c
> > index faa94adb2a37..65ab5c2f48b0 100644
> > --- a/drivers/clk/rockchip/clk-rk3328.c
> > +++ b/drivers/clk/rockchip/clk-rk3328.c
> > @@ -78,17 +78,17 @@ static struct rockchip_pll_rate_table rk3328_pll_rates[] = {
> >
> > static struct rockchip_pll_rate_table rk3328_pll_frac_rates[] = {
> > /* _mhz, _refdiv, _fbdiv, _postdiv1, _postdiv2, _dsmpd, _frac */
> > - RK3036_PLL_RATE(1016064000, 3, 127, 1, 1, 0, 134217),
> > + RK3036_PLL_RATE(1016064000, 3, 127, 1, 1, 0, 134218),
> > /* vco = 1016064000 */
> > - RK3036_PLL_RATE(983040000, 24, 983, 1, 1, 0, 671088),
> > + RK3036_PLL_RATE(983040000, 24, 983, 1, 1, 0, 671089),
> > /* vco = 983040000 */
> > - RK3036_PLL_RATE(491520000, 24, 983, 2, 1, 0, 671088),
> > + RK3036_PLL_RATE(491520000, 24, 983, 2, 1, 0, 671089),
> > /* vco = 983040000 */
> > - RK3036_PLL_RATE(61440000, 6, 215, 7, 2, 0, 671088),
> > + RK3036_PLL_RATE(61440000, 6, 215, 7, 2, 0, 671089),
> > /* vco = 860156000 */
> > - RK3036_PLL_RATE(56448000, 12, 451, 4, 4, 0, 9797894),
> > + RK3036_PLL_RATE(56448000, 12, 451, 4, 4, 0, 9797895),
> > /* vco = 903168000 */
> > - RK3036_PLL_RATE(40960000, 12, 409, 4, 5, 0, 10066329),
> > + RK3036_PLL_RATE(40960000, 12, 409, 4, 5, 0, 10066330),
> > /* vco = 819200000 */
> > { /* sentinel */ },
> > };
> >
>
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