Messages in this thread | | | Date | Tue, 07 May 2013 12:07:39 +0200 | From | Sebastian Hesselbarth <> | Subject | Re: [PATCH 2/2] clk: si5351: Powerdown output when clock rate is 0. |
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On 05/07/2013 10:14 AM, Marek Belisko wrote: > When rate is 0 powerdown clock output. > > Signed-off-by: Marek Belisko<marek.belisko@streamunlimited.com> > --- > 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.
> + 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",
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