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Re: [PATCH 7/9] net: ethernet: ti: cpts: calc mult and shift from refclk freq

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On Wed, Sep 14, 2016 at 11:47:46PM +0300, Grygorii Strashko wrote:
> As I understand (and tested), clocks_calc_mult_shift() will 
> return max possible mult which can be used without overflow.

Yes, BUT the returned values depends on the @maxsec input.  As the
kerneldec says,

 * Larger ranges may reduce the conversion accuracy by chosing smaller
 * mult and shift factors.

In addition to that, frequency tuning by calculating a percentage of
'mult', and if 'mult' is small, then the tuning resolution is poor.

So we don't want @maxsec as large as possible, but as small as
possible.

> if calculated results do not satisfy end user - the custom values can
> be passed in DT.  

If we calculate automatically, then the result had better well be
optimal or nearly so.  Otherwise, we should leave it as a manual input
via DTS, IMHO, so that someone is forced to check the values.

Thanks,
Richard

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[PATCH 0/9] net: ethernet: ti: cpts: update and fixes Grygorii Strashko <grygorii.strashko@ti.com> - 2016-09-14 15:10 +0200
  [PATCH 8/9] net: ethernet: ti: cpts: fix overflow check period Grygorii Strashko <grygorii.strashko@ti.com> - 2016-09-14 15:10 +0200
    Re: [PATCH 8/9] net: ethernet: ti: cpts: fix overflow check period Richard Cochran <richardcochran@gmail.com> - 2016-09-14 16:30 +0200
      Re: [PATCH 8/9] net: ethernet: ti: cpts: fix overflow check period Richard Cochran <richardcochran@gmail.com> - 2016-09-14 22:10 +0200
        Re: [PATCH 8/9] net: ethernet: ti: cpts: fix overflow check period Grygorii Strashko <grygorii.strashko@ti.com> - 2016-09-14 22:30 +0200
          Re: [PATCH 8/9] net: ethernet: ti: cpts: fix overflow check period Richard Cochran <richardcochran@gmail.com> - 2016-09-14 22:50 +0200
            Re: [PATCH 8/9] net: ethernet: ti: cpts: fix overflow check period Grygorii Strashko <grygorii.strashko@ti.com> - 2016-09-14 23:00 +0200
      Re: [PATCH 8/9] net: ethernet: ti: cpts: fix overflow check period Grygorii Strashko <grygorii.strashko@ti.com> - 2016-09-14 22:10 +0200
  [PATCH 7/9] net: ethernet: ti: cpts: calc mult and shift from refclk freq Grygorii Strashko <grygorii.strashko@ti.com> - 2016-09-14 15:10 +0200
    Re: [PATCH 7/9] net: ethernet: ti: cpts: calc mult and shift from  refclk freq Richard Cochran <richardcochran@gmail.com> - 2016-09-14 16:30 +0200
      Re: [PATCH 7/9] net: ethernet: ti: cpts: calc mult and shift from  refclk freq Grygorii Strashko <grygorii.strashko@ti.com> - 2016-09-14 22:10 +0200
    Re: [PATCH 7/9] net: ethernet: ti: cpts: calc mult and shift from  refclk freq Richard Cochran <richardcochran@gmail.com> - 2016-09-14 22:30 +0200
      Re: [PATCH 7/9] net: ethernet: ti: cpts: calc mult and shift from  refclk freq Grygorii Strashko <grygorii.strashko@ti.com> - 2016-09-14 23:00 +0200
        Re: [PATCH 7/9] net: ethernet: ti: cpts: calc mult and shift from  refclk freq Richard Cochran <richardcochran@gmail.com> - 2016-09-14 23:10 +0200
          Re: [PATCH 7/9] net: ethernet: ti: cpts: calc mult and shift from  refclk freq Grygorii Strashko <grygorii.strashko@ti.com> - 2016-09-14 23:20 +0200
      Re: [PATCH 7/9] net: ethernet: ti: cpts: calc mult and shift from  refclk freq Richard Cochran <richardcochran@gmail.com> - 2016-09-15 14:00 +0200
        Re: [PATCH 7/9] net: ethernet: ti: cpts: calc mult and shift from  refclk freq Richard Cochran <richardcochran@gmail.com> - 2016-09-15 16:00 +0200
  [PATCH 1/9] net: ethernet: ti: exclude cpts from build when disabled Grygorii Strashko <grygorii.strashko@ti.com> - 2016-09-14 15:10 +0200
  [PATCH 3/9] net: ethernet: ti: cpts: rework initialization/deinitialization Grygorii Strashko <grygorii.strashko@ti.com> - 2016-09-14 15:10 +0200
    Re: [PATCH 3/9] net: ethernet: ti: cpts: rework  initialization/deinitialization Richard Cochran <richardcochran@gmail.com> - 2016-09-14 16:00 +0200
      Re: [PATCH 3/9] net: ethernet: ti: cpts: rework  initialization/deinitialization Grygorii Strashko <grygorii.strashko@ti.com> - 2016-09-14 22:20 +0200
        Re: [PATCH 3/9] net: ethernet: ti: cpts: rework  initialization/deinitialization Grygorii Strashko <grygorii.strashko@ti.com> - 2016-09-14 22:40 +0200
          Re: [PATCH 3/9] net: ethernet: ti: cpts: rework  initialization/deinitialization Richard Cochran <richardcochran@gmail.com> - 2016-09-14 23:00 +0200
            Re: [PATCH 3/9] net: ethernet: ti: cpts: rework  initialization/deinitialization Grygorii Strashko <grygorii.strashko@ti.com> - 2016-09-14 23:00 +0200
        Re: [PATCH 3/9] net: ethernet: ti: cpts: rework  initialization/deinitialization Richard Cochran <richardcochran@gmail.com> - 2016-09-14 22:40 +0200
    Re: [PATCH 3/9] net: ethernet: ti: cpts: rework  initialization/deinitialization Richard Cochran <richardcochran@gmail.com> - 2016-09-15 10:20 +0200
  [PATCH 5/9] net: ethernet: ti: cpts: add return value to tx and rx timestamp funcitons Grygorii Strashko <grygorii.strashko@ti.com> - 2016-09-14 15:10 +0200
    Re: [PATCH 5/9] net: ethernet: ti: cpts: add return value to tx and  rx timestamp funcitons Richard Cochran <richardcochran@gmail.com> - 2016-09-14 16:10 +0200
  [PATCH 6/9] net: ethernet: ti: cpts: clean up event list if event pool is empty Grygorii Strashko <grygorii.strashko@ti.com> - 2016-09-14 15:10 +0200
    Re: [PATCH 6/9] net: ethernet: ti: cpts: clean up event list if  event pool is empty Richard Cochran <richardcochran@gmail.com> - 2016-09-14 16:20 +0200
      Re: [PATCH 6/9] net: ethernet: ti: cpts: clean up event list if event  pool is empty Grygorii Strashko <grygorii.strashko@ti.com> - 2016-09-14 22:00 +0200

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