Re: [PATCH] clk: ti: divider: Add the table parsing to get the best divider value

[Tero Kristo]

On 25/01/17 12:37, Keerthy wrote:
> On Friday 02 December 2016 02:35 PM, Keerthy wrote:
> > Currently the divider selection logic blindly divides the parent_rate
> > by the clk rate and gives the divider value for the divider clocks
> > which do not have the CLK_SET_RATE_PARENT flag set. Add the clk divider
> > table parsing to get the closest divider available in the table
> > provided via Device tree.
> >
> > The code is pretty much taken from: drivers/clk/clk-divider.c.
> > and used here to fix up the best divider selection logic.
>
> A gentle ping on this patch. This applies cleanly on the next branch as
> on today. Let me know if this needs to be rebased.
>
> - Keerthy
>
> > Signed-off-by: Keerthy <j-keerthy@xxxxxx>
> > Reported-by: Richard Woodruff <r-woodruff2@xxxxxx>

Acked-by: Tero Kristo <t-kristo@xxxxxx>

Stephen / Michael, can you pick this up?

-Tero

> > ---
> >  drivers/clk/ti/divider.c | 31 ++++++++++++++++++++++++++++++-
> >  1 file changed, 30 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/clk/ti/divider.c b/drivers/clk/ti/divider.c
> > index b4e5de1..6bb8778 100644
> > --- a/drivers/clk/ti/divider.c
> > +++ b/drivers/clk/ti/divider.c
> > @@ -140,6 +140,35 @@ static bool _is_valid_div(struct clk_divider
> > *divider, unsigned int div)
> >      return true;
> >  }
> >
> > +static int _div_round_up(const struct clk_div_table *table,
> > +             unsigned long parent_rate, unsigned long rate)
> > +{
> > +    const struct clk_div_table *clkt;
> > +    int up = INT_MAX;
> > +    int div = DIV_ROUND_UP_ULL((u64)parent_rate, rate);
> > +
> > +    for (clkt = table; clkt->div; clkt++) {
> > +        if (clkt->div == div)
> > +            return clkt->div;
> > +        else if (clkt->div < div)
> > +            continue;
> > +
> > +        if ((clkt->div - div) < (up - div))
> > +            up = clkt->div;
> > +    }
> > +
> > +    return up;
> > +}
> > +
> > +static int _div_round(const struct clk_div_table *table,
> > +              unsigned long parent_rate, unsigned long rate)
> > +{
> > +    if (!table)
> > +        return DIV_ROUND_UP(parent_rate, rate);
> > +
> > +    return _div_round_up(table, parent_rate, rate);
> > +}
> > +
> >  static int ti_clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate,
> >                    unsigned long *best_parent_rate)
> >  {
> > @@ -155,7 +184,7 @@ static int ti_clk_divider_bestdiv(struct clk_hw
> > *hw, unsigned long rate,
> >
> >      if (!(clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT)) {
> >          parent_rate = *best_parent_rate;
> > -        bestdiv = DIV_ROUND_UP(parent_rate, rate);
> > +        bestdiv = _div_round(divider->table, parent_rate, rate);
> >          bestdiv = bestdiv == 0 ? 1 : bestdiv;
> >          bestdiv = bestdiv > maxdiv ? maxdiv : bestdiv;
> >          return bestdiv;