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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Jonathan Corbet , "open list:DOCUMENTATION" , open list References: <20250910103221.347108-1-ivecera@redhat.com> <0817610a-e3dd-427e-b0ad-c2d503bb8a4f@redhat.com> <10886c5f-1265-46ec-8caa-41bde6888905@lunn.ch> Content-Language: en-US From: Ivan Vecera In-Reply-To: <10886c5f-1265-46ec-8caa-41bde6888905@lunn.ch> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 On 10. 09. 25 7:06 odp., Andrew Lunn wrote: > On Wed, Sep 10, 2025 at 06:50:47PM +0200, Ivan Vecera wrote: >> 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 >>>> Signed-off-by: Ivan Vecera >>>> --- >>>> 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. > > So what if it is long? At the moment, it is hiding in the commit > message. It is not easy to find, you effectively need to be a kernel > developer to find it. If it is in the documentation of the device, it > will be much easier to find and understand what this knob actually > does. > Agree. I will describe it in more detail in the documentation. + optimization proposed by Vadim. Thanks for the review. Ivan