Re: [PATCH 2/2] clk: si5351: Powerdown output when clock rate is0.

[Marek Belisko]

On 05/07/2013 12:07 PM, Sebastian Hesselbarth wrote:
> On 05/07/2013 10:14 AM, Marek Belisko wrote:
> > When rate is 0 powerdown clock output.
> >
> > Signed-off-by: Marek Belisko<marek.belisko@xxxxxxxxxxxxxxxxxxx>
> > ---
> >   drivers/clk/clk-si5351.c |   32 +++++++++++++++++++-------------
> >   1 file changed, 19 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/clk/clk-si5351.c b/drivers/clk/clk-si5351.c
> > index a8fc0f4..e254e76 100644
> > --- a/drivers/clk/clk-si5351.c
> > +++ b/drivers/clk/clk-si5351.c
> > @@ -1042,20 +1042,22 @@ static int si5351_clkout_set_rate(struct
> > clk_hw *hw, unsigned long rate,
> >       struct si5351_hw_data *hwdata =
> >           container_of(hw, struct si5351_hw_data, hw);
> >       unsigned long new_rate, new_err, err;
> > -    unsigned char rdiv;
> > +    unsigned char rdiv, pdn = 0;
> >
> >       /* round to closed rdiv */
> >       rdiv = SI5351_OUTPUT_CLK_DIV_1;
> > -    new_rate = parent_rate;
> > -    err = abs(new_rate - rate);
> > -    do {
> > -        new_rate>>= 1;
> > -        new_err = abs(new_rate - rate);
> > -        if (new_err>  err || rdiv == SI5351_OUTPUT_CLK_DIV_128)
> > -            break;
> > -        rdiv++;
> > -        err = new_err;
> > -    } while (1);
> > +    if (rate) {
> > +        new_rate = parent_rate;
>
> Marek,
>
> initalizing pdn to SI5351_CLK_POWERDOWN and skip (with goto) to
> powerup/down call on zero rate will save us a level of indention here.
OK will fix and resubmit in v2. Thanks.
> > +        err = abs(new_rate - rate);
> > +        do {
> > +            new_rate>>= 1;
> > +            new_err = abs(new_rate - rate);
> > +            if (new_err>  err || rdiv == SI5351_OUTPUT_CLK_DIV_128)
> > +                break;
> > +            rdiv++;
> > +            err = new_err;
> > +        } while (1);
>
> of course, pdn should be set to 0 here.
>
> > +    }
> >
> >       /* write output divider */
> >       switch (hwdata->num) {
> > @@ -1075,9 +1077,13 @@ static int si5351_clkout_set_rate(struct clk_hw
> > *hw, unsigned long rate,
> >                   rdiv<<  SI5351_OUTPUT_CLK_DIV_SHIFT);
> >       }
> >
> > -    /* powerup clkout */
> > +    /* when rate is 0 powerdown output */
> > +    if (rate == 0)
> > +        pdn = SI5351_CLK_POWERDOWN;
> > +
> > +    /* powerup/down clkout */
> >       si5351_set_bits(hwdata->drvdata, SI5351_CLK0_CTRL + hwdata->num,
> > -            SI5351_CLK_POWERDOWN, 0);
> > +            SI5351_CLK_POWERDOWN, pdn);
> >
> >       dev_dbg(&hwdata->drvdata->client->dev,
> >           "%s - %s: rdiv = %u, parent_rate = %lu, rate = %lu\n",

marek
--
Marek Belisko

Software Developer
StreamUnlimited Engineering GmbH
Gutheil Schodergasse 8-12
A-1100 Vienna, Austria

Office: +421 267200087

e-mail: marek.belisko@xxxxxxxxxxxxxxxxxxx
http://www.streamunlimited.com

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