Re: [PATCH v4 3/8] clk: samsung: add infrastructure to register cpu clocks

["Heiko Stübner" <heiko@sntech.de>]

Am Donnerstag, 15. Mai 2014, 11:18:44 schrieb Doug Anderson:
> Thomas,
> 
> On Tue, May 13, 2014 at 6:11 PM, Thomas Abraham <ta.omasab@gmail.com> wrote:
> > From: Thomas Abraham <thomas.ab@samsung.com>
> > +static int exynos4210_armclk_pre_rate_change(struct clk_notifier_data
> > *ndata, +                       struct exynos_cpuclk *armclk, void
> > __iomem *base) +{
> > +       struct exynos4210_armclk_data *armclk_data = armclk->data;
> > +       unsigned long alt_prate = clk_get_rate(armclk->alt_parent);
> > +       unsigned long alt_div, div0, div1, tdiv0, mux_reg;
> > +       unsigned long cur_armclk_rate, timeout;
> > +       unsigned long flags;
> > +
> > +       /* find out the divider values to use for clock data */
> > +       while (armclk_data->prate != ndata->new_rate) {
> > +               if (armclk_data->prate == 0)
> > +                       return -EINVAL;
> > +               armclk_data++;
> > +       }
> > +
> > +       div0 = armclk_data->div0;
> > +       div1 = armclk_data->div1;
> > +       if (readl(base + SRC_CPU) & EXYNOS4210_MUX_HPM_MASK) {
> > +               div1 = readl(base + DIV_CPU1) & EXYNOS4210_DIV1_HPM_MASK;
> > +               div1 |= ((armclk_data->div1) & ~EXYNOS4210_DIV1_HPM_MASK);
> > +       }
> > +
> > +       /*
> > +        * if the new and old parent clock speed is less than the clock
> > speed +        * of the alternate parent, then it should be ensured that
> > at no point +        * the armclk speed is more than the old_prate until
> > the dividers are +        * set.
> > +        */
> > +       tdiv0 = readl(base + DIV_CPU0);
> > +       cur_armclk_rate = ndata->old_rate / EXYNOS4210_ARM_DIV1(tdiv0) /
> > +                               EXYNOS4210_ARM_DIV2(tdiv0);
> > +       if (alt_prate > cur_armclk_rate) {
> > +               alt_div = _calc_div(alt_prate, cur_armclk_rate);
> > +               _exynos4210_set_armclk_div(base, alt_div);
> > +               div0 |= alt_div;
> 
> Don't you need to up the voltage here, too?  ...I haven't reviewed
> this whole patch (so perhaps it's elsewhere in the patch or in the
> series), but I stumbled upon this while trying to solve a different
> problem and figured I'd check...

setting the voltage should be done by the cpufreq driver like cpufreq-cpu0 - 
whose usage this series intents to allow.

As I've hijacked Thomas' concept for my current rockchip clock work, I've 
already seen this working nicely :-) .


Heiko