diff options
| author | Ivan Vecera <ivecera@redhat.com> | 2025-09-27 10:49:10 +0200 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2025-09-29 18:57:41 -0700 |
| commit | a680581f6a131fd8c62d284ed4a24d4bc1cc553e (patch) | |
| tree | be0eab91061a7c5dafd1732a0618dccd833c70c7 /Documentation/driver-api | |
| parent | 377ea331281f2c63dc281a6ea2dc318e4e1fc2d1 (diff) | |
| download | linux-a680581f6a131fd8c62d284ed4a24d4bc1cc553e.tar.gz | |
dpll: add phase-offset-avg-factor device attribute to netlink spec
Add dpll device level attribute DPLL_A_PHASE_OFFSET_AVG_FACTOR to allow
control over a calculation of reported phase offset value. Attribute is
present, if the driver provides such capability, otherwise attribute
shall not be present.
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Link: https://patch.msgid.link/20250927084912.2343597-2-ivecera@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'Documentation/driver-api')
| -rw-r--r-- | Documentation/driver-api/dpll.rst | 18 |
1 files changed, 17 insertions, 1 deletions
diff --git a/Documentation/driver-api/dpll.rst b/Documentation/driver-api/dpll.rst index eca72d9b9ed874..be1fc643b645e3 100644 --- a/Documentation/driver-api/dpll.rst +++ b/Documentation/driver-api/dpll.rst @@ -179,7 +179,23 @@ Phase offset measurement and adjustment Device may provide ability to measure a phase difference between signals on a pin and its parent dpll device. If pin-dpll phase offset measurement is supported, it shall be provided with ``DPLL_A_PIN_PHASE_OFFSET`` -attribute for each parent dpll device. +attribute for each parent dpll device. The reported phase offset may be +computed as the average of prior values and the current measurement, using +the following formula: + +.. math:: + curr\_avg = prev\_avg * \frac{2^N-1}{2^N} + new\_val * \frac{1}{2^N} + +where `curr_avg` is the current reported phase offset, `prev_avg` is the +previously reported value, `new_val` is the current measurement, and `N` is +the averaging factor. Configured averaging factor value is provided with +``DPLL_A_PHASE_OFFSET_AVG_FACTOR`` attribute of a device and value change can +be requested with the same attribute with ``DPLL_CMD_DEVICE_SET`` command. + + ================================== ====================================== + ``DPLL_A_PHASE_OFFSET_AVG_FACTOR`` attr configured value of phase offset + averaging factor + ================================== ====================================== Device may also provide ability to adjust a signal phase on a pin. If pin phase adjustment is supported, minimal and maximal values that pin |