Re: [PATCH] cpufreq: imx6q: Fix imx6sx low frequency support
From: Rafael J. Wysocki
Date: Wed Aug 30 2017 - 19:40:27 EST
On Monday, August 28, 2017 2:07:51 PM CEST Lucas Stach wrote:
> Am Montag, den 28.08.2017, 14:05 +0300 schrieb Leonard Crestez:
> > This patch contains the minimal changes required to support imx6sx OPP
> > of 198 Mhz. Without this patch cpufreq still reports success but the
> > frequency is not changed, the "arm" clock will still be at 396000000 in
> > clk_summary.
> >
> > In order to do this PLL1 needs to be still kept enabled while changing
> > the ARM clock. This is a hardware requirement: when ARM_PODF is changed
> > in CCM we need to check the busy bit of CCM_CDHIPR bit 16 arm_podf_busy,
> > and this bit is sync with PLL1 clock, so if PLL1 NOT enabled, this
> > bit will never get clear.
> >
> > Keep pll1_sys explicitly enabled until after the rate is change to deal
> > with this. Otherwise from the clk framework perspective pll1_sys is
> > unused and gets turned off.
> >
> > Signed-off-by: Leonard Crestez <leonard.crestez@xxxxxxx>
>
> Reviewed-by: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
Patch applied, thanks!