[PATCH v2 01/16] clk: sunxi-ng: Add check for minimal rate to NM PLLs

Jernej Škrabec
2018-02-28T21:55:03Z

Hi,

Dne sreda, 28. februar 2018 ob 08:34:40 CET je Maxime Ripard napisal(a):
> Hi,
>
> On Tue, Feb 27, 2018 at 11:26:46PM +0100, Jernej Skrabec wrote:
> > Some NM PLLs doesn't work well when their output clock rate is set below
> > certain rate.
> >
> > Add support for that constrain.
> >
> > Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
> > ---
> >
> > drivers/clk/sunxi-ng/ccu_nm.c | 11 +++++++----
> > drivers/clk/sunxi-ng/ccu_nm.h | 27 +++++++++++++++++++++++++++
> > 2 files changed, 34 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/clk/sunxi-ng/ccu_nm.c b/drivers/clk/sunxi-ng/ccu_nm.c
> > index a16de092bf94..7fc743c78c1b 100644
> > --- a/drivers/clk/sunxi-ng/ccu_nm.c
> > +++ b/drivers/clk/sunxi-ng/ccu_nm.c
> > @@ -20,7 +20,7 @@ struct _ccu_nm {
> >
> > };
> >
> > static void ccu_nm_find_best(unsigned long parent, unsigned long rate,
> >
> > - struct _ccu_nm *nm)
> > + unsigned long min_rate, struct _ccu_nm *nm)
> >
> > {
> >
> > unsigned long best_rate = 0;
> > unsigned long best_n = 0, best_m = 0;
> >
> > @@ -30,7 +30,7 @@ static void ccu_nm_find_best(unsigned long parent,
> > unsigned long rate,>
> > for (_m = nm->min_m; _m <= nm->max_m; _m++) {
> >
> > unsigned long tmp_rate = parent * _n / _m;
> >
> > - if (tmp_rate > rate)
> > + if (tmp_rate > rate || tmp_rate < min_rate)
> >
> > continue;
> >
> > if ((rate - tmp_rate) < (rate - best_rate)) {
> >
> > @@ -117,6 +117,9 @@ static long ccu_nm_round_rate(struct clk_hw *hw,
> > unsigned long rate,>
> > if (nm->common.features & CCU_FEATURE_FIXED_POSTDIV)
> >
> > rate *= nm->fixed_post_div;
> >
> > + if (rate < nm->min_rate)
> > + rate = nm->min_rate;
> > +
>
> I guess you can just return there. There's no point in trying to find
> the factors at this point, since the minimum should be a value that
> can be reached.
>

Right, I already tested it and it works.

Best regards,
Jernej

> > if (ccu_frac_helper_has_rate(&nm->common, &nm->frac, rate)) {
> >
> > if (nm->common.features & CCU_FEATURE_FIXED_POSTDIV)
> >
> > rate /= nm->fixed_post_div;
> >
> > @@ -134,7 +137,7 @@ static long ccu_nm_round_rate(struct clk_hw *hw,
> > unsigned long rate,>
> > _nm.min_m = 1;
> > _nm.max_m = nm->m.max ?: 1 << nm->m.width;
> >
> > - ccu_nm_find_best(*parent_rate, rate, &_nm);
> > + ccu_nm_find_best(*parent_rate, rate, nm->min_rate, &_nm);
>
> Therefore, you don't need to change the prototype there either.
>
> Maxime
>
> --
> Maxime Ripard, Bootlin (formerly Free Electrons)
> Embedded Linux and Kernel engineering
> https://bootlin.com