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SubjectRe: [PATCH 2/2] clk: si5351: Powerdown output when clock rate is 0.
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@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.
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@streamunlimited.com
http://www.streamunlimited.com

Meet us at:

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