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Re: [PATCH v2 12/13] net: ethernet: ti: cpts: calc mult and shift from refclk freq

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On 11/29/2016 04:34 AM, Richard Cochran wrote:
> On Mon, Nov 28, 2016 at 05:03:36PM -0600, Grygorii Strashko wrote:
>> +static void cpts_calc_mult_shift(struct cpts *cpts)
>> +{
>> +	u64 frac, maxsec, ns;
>> +	u32 freq, mult, shift;
>> +
>> +	freq = clk_get_rate(cpts->refclk);
>> +
>> +	/* Calc the maximum number of seconds which we can run before
>> +	 * wrapping around.
>> +	 */
>> +	maxsec = cpts->cc.mask;
>> +	do_div(maxsec, freq);
>> +	if (maxsec > 600 && cpts->cc.mask > UINT_MAX)
>> +		maxsec = 600;
> 
> The reason for this test is not obvious.  Why check cc.mask against
> UINT_MAX?  Please use the comment to explain it.
> 

Yeah. This is copy paste from __clocksource_update_freq_scale(), but
I'm going to limit it to 10 sec for now, because otherwise it will result in too small
mult in case of 64bit counter.

if (maxsec > 10)
	maxsec = 10;

-- 
regards,
-grygorii

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[PATCH v2 00/13] net: ethernet: ti: cpts: update and fixes Grygorii Strashko <grygorii.strashko@ti.com> - 2016-11-29 00:10 +0100
  [PATCH  v2 12/13] net: ethernet: ti: cpts: calc mult and shift from refclk freq Grygorii Strashko <grygorii.strashko@ti.com> - 2016-11-29 00:10 +0100
    Re: [PATCH  v2 12/13] net: ethernet: ti: cpts: calc mult and shift  from refclk freq Richard Cochran <richardcochran@gmail.com> - 2016-11-29 11:40 +0100
      Re: [PATCH v2 12/13] net: ethernet: ti: cpts: calc mult and shift  from refclk freq Grygorii Strashko <grygorii.strashko@ti.com> - 2016-11-29 17:30 +0100
  [PATCH  v2 03/13] net: ethernet: ti: cpsw: minimize direct access to struct cpts Grygorii Strashko <grygorii.strashko@ti.com> - 2016-11-29 00:10 +0100
  [PATCH v2 10/13] net: ethernet: ti: cpts: drop excessive writes to CTRL and INT_EN regs Grygorii Strashko <grygorii.strashko@ti.com> - 2016-11-29 00:10 +0100
    Re: [PATCH v2 10/13] net: ethernet: ti: cpts: drop excessive writes  to CTRL and INT_EN regs Richard Cochran <richardcochran@gmail.com> - 2016-11-29 11:20 +0100
  [PATCH  v2 06/13] net: ethernet: ti: cpts: disable cpts when unregistered Grygorii Strashko <grygorii.strashko@ti.com> - 2016-11-29 00:10 +0100
    Re: [PATCH  v2 06/13] net: ethernet: ti: cpts: disable cpts when  unregistered Richard Cochran <richardcochran@gmail.com> - 2016-11-29 11:00 +0100
  [PATCH  v2 07/13] net: ethernet: ti: cpts: rework initialization/deinitialization Grygorii Strashko <grygorii.strashko@ti.com> - 2016-11-29 00:10 +0100
    Re: [PATCH  v2 07/13] net: ethernet: ti: cpts: rework  initialization/deinitialization Richard Cochran <richardcochran@gmail.com> - 2016-11-29 11:10 +0100
      Re: [PATCH v2 07/13] net: ethernet: ti: cpts: rework  initialization/deinitialization Grygorii Strashko <grygorii.strashko@ti.com> - 2016-11-29 17:00 +0100
        Re: [PATCH v2 07/13] net: ethernet: ti: cpts: rework  initialization/deinitialization Grygorii Strashko <grygorii.strashko@ti.com> - 2016-11-30 19:40 +0100
  [PATCH  v2 02/13] net: ethernet: ti: allow cpts to be built separately Grygorii Strashko <grygorii.strashko@ti.com> - 2016-11-29 00:10 +0100
    Re: [PATCH  v2 02/13] net: ethernet: ti: allow cpts to be built  separately Richard Cochran <richardcochran@gmail.com> - 2016-11-29 10:40 +0100
  [PATCH  v2 01/13] net: ethernet: ti: cpts: switch to readl/writel_relaxed() Grygorii Strashko <grygorii.strashko@ti.com> - 2016-11-29 00:10 +0100
    Re: [PATCH  v2 01/13] net: ethernet: ti: cpts: switch to  readl/writel_relaxed() Richard Cochran <richardcochran@gmail.com> - 2016-11-29 10:40 +0100
  [PATCH  v2 13/13] net: ethernet: ti: cpts: fix overflow check period Grygorii Strashko <grygorii.strashko@ti.com> - 2016-11-29 00:10 +0100
    Re: [PATCH  v2 13/13] net: ethernet: ti: cpts: fix overflow check  period Richard Cochran <richardcochran@gmail.com> - 2016-11-30 10:20 +0100
  [PATCH  v2 11/13] clocksource: export the clocks_calc_mult_shift to use by timestamp code Grygorii Strashko <grygorii.strashko@ti.com> - 2016-11-29 00:10 +0100
    Re: [PATCH v2 11/13] clocksource: export the clocks_calc_mult_shift  to use by timestamp code Thomas Gleixner <tglx@linutronix.de> - 2016-11-29 10:20 +0100
  [PATCH  v2 09/13] net: ethernet: ti: cpts: clean up event list if event pool is empty Grygorii Strashko <grygorii.strashko@ti.com> - 2016-11-29 00:20 +0100
    Re: [PATCH  v2 09/13] net: ethernet: ti: cpts: clean up event list  if event pool is empty Richard Cochran <richardcochran@gmail.com> - 2016-11-29 11:20 +0100
  [PATCH  v2 04/13] net: ethernet: ti: cpts: fix unbalanced clk api usage in cpts_register/unregister Grygorii Strashko <grygorii.strashko@ti.com> - 2016-11-29 00:20 +0100
    Re: [PATCH  v2 04/13] net: ethernet: ti: cpts: fix unbalanced clk  api usage in cpts_register/unregister Richard Cochran <richardcochran@gmail.com> - 2016-11-29 10:50 +0100
  [PATCH  v2 08/13] net: ethernet: ti: cpts: move dt props parsing to cpts driver Grygorii Strashko <grygorii.strashko@ti.com> - 2016-11-29 00:20 +0100
    Re: [PATCH  v2 08/13] net: ethernet: ti: cpts: move dt props parsing  to cpts driver Richard Cochran <richardcochran@gmail.com> - 2016-11-29 11:20 +0100
      Re: [PATCH v2 08/13] net: ethernet: ti: cpts: move dt props parsing  to cpts driver Grygorii Strashko <grygorii.strashko@ti.com> - 2016-11-29 17:00 +0100
  [PATCH  v2 05/13] net: ethernet: ti: cpts: fix registration order Grygorii Strashko <grygorii.strashko@ti.com> - 2016-11-29 00:20 +0100
    Re: [PATCH  v2 05/13] net: ethernet: ti: cpts: fix registration order Richard Cochran <richardcochran@gmail.com> - 2016-11-29 10:50 +0100

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