Re: [PATCH net-next] dpll: zl3073x: Allow to use custom phase measure averaging factor

[Ivan Vecera <ivecera@redhat.com>]

On 10. 09. 25 6:13 odp., Andrew Lunn wrote:
> On Wed, Sep 10, 2025 at 12:32:21PM +0200, Ivan Vecera wrote:
>> The DPLL phase measurement block uses an exponential moving average,
>> calculated using the following equation:
>>
>>                         2^N - 1                1
>> curr_avg = prev_avg * --------- + new_val * -----
>>                           2^N                 2^N
>>
>> Where curr_avg is phase offset reported by the firmware to the driver,
>> prev_avg is previous averaged value and new_val is currently measured
>> value for particular reference.
>>
>> New measurements are taken approximately 40 Hz or at the frequency of
>> the reference (whichever is lower).
>>
>> The driver currently uses the averaging factor N=2 which prioritizes
>> a fast response time to track dynamic changes in the phase. But for
>> applications requiring a very stable and precise reading of the average
>> phase offset, and where rapid changes are not expected, a higher factor
>> would be appropriate.
>>
>> Add devlink device parameter phase_offset_avg_factor to allow a user
>> set tune the averaging factor via devlink interface.
>>
>> Tested-by: Prathosh Satish <Prathosh.Satish@microchip.com>
>> Signed-off-by: Ivan Vecera <ivecera@redhat.com>
>> ---
>>   Documentation/networking/devlink/zl3073x.rst |  4 ++
>>   drivers/dpll/zl3073x/core.c                  |  6 +-
>>   drivers/dpll/zl3073x/core.h                  |  8 ++-
>>   drivers/dpll/zl3073x/devlink.c               | 67 ++++++++++++++++++++
>>   4 files changed, 82 insertions(+), 3 deletions(-)
>>
>> diff --git a/Documentation/networking/devlink/zl3073x.rst b/Documentation/networking/devlink/zl3073x.rst
>> index 4b6cfaf386433..ddd159e39e616 100644
>> --- a/Documentation/networking/devlink/zl3073x.rst
>> +++ b/Documentation/networking/devlink/zl3073x.rst
>> @@ -20,6 +20,10 @@ Parameters
>>        - driverinit
>>        - Set the clock ID that is used by the driver for registering DPLL devices
>>          and pins.
>> +   * - ``phase_offset_avg_factor``
>> +     - runtime
>> +     - Set the factor for the exponential moving average used by DPLL phase
>> +       measurement block. The value has to be in range <0, 15>.
> 
> Maybe put the text in the commit message here as well?

Do you mean to put the equation and details from commit message here?
This is pretty long.

Ivan