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 --- Documentation/driver-api/dpll.rst | 18 +++++++++++++++++- Documentation/netlink/specs/dpll.yaml | 6 ++++++ drivers/dpll/dpll_nl.c | 5 +++-- include/uapi/linux/dpll.h | 1 + 4 files changed, 27 insertions(+), 3 deletions(-) diff --git a/Documentation/driver-api/dpll.rst b/Documentation/driver-api/dpll.rst index eca72d9b9ed87..be1fc643b645e 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 diff --git a/Documentation/netlink/specs/dpll.yaml b/Documentation/netlink/specs/dpll.yaml index 5decee61a2c4c..cafb4ec20447e 100644 --- a/Documentation/netlink/specs/dpll.yaml +++ b/Documentation/netlink/specs/dpll.yaml @@ -315,6 +315,10 @@ attribute-sets: If enabled, dpll device shall monitor and notify all currently available inputs for changes of their phase offset against the dpll device. + - + name: phase-offset-avg-factor + type: u32 + doc: Averaging factor applied to calculation of reported phase offset. - name: pin enum-name: dpll_a_pin @@ -523,6 +527,7 @@ operations: - clock-id - type - phase-offset-monitor + - phase-offset-avg-factor dump: reply: *dev-attrs @@ -540,6 +545,7 @@ operations: attributes: - id - phase-offset-monitor + - phase-offset-avg-factor - name: device-create-ntf doc: Notification about device appearing diff --git a/drivers/dpll/dpll_nl.c b/drivers/dpll/dpll_nl.c index 9f2efaf252688..3c6d570babf89 100644 --- a/drivers/dpll/dpll_nl.c +++ b/drivers/dpll/dpll_nl.c @@ -42,9 +42,10 @@ static const struct nla_policy dpll_device_get_nl_policy[DPLL_A_ID + 1] = { }; /* DPLL_CMD_DEVICE_SET - do */ -static const struct nla_policy dpll_device_set_nl_policy[DPLL_A_PHASE_OFFSET_MONITOR + 1] = { +static const struct nla_policy dpll_device_set_nl_policy[DPLL_A_PHASE_OFFSET_AVG_FACTOR + 1] = { [DPLL_A_ID] = { .type = NLA_U32, }, [DPLL_A_PHASE_OFFSET_MONITOR] = NLA_POLICY_MAX(NLA_U32, 1), + [DPLL_A_PHASE_OFFSET_AVG_FACTOR] = { .type = NLA_U32, }, }; /* DPLL_CMD_PIN_ID_GET - do */ @@ -112,7 +113,7 @@ static const struct genl_split_ops dpll_nl_ops[] = { .doit = dpll_nl_device_set_doit, .post_doit = dpll_post_doit, .policy = dpll_device_set_nl_policy, - .maxattr = DPLL_A_PHASE_OFFSET_MONITOR, + .maxattr = DPLL_A_PHASE_OFFSET_AVG_FACTOR, .flags = GENL_ADMIN_PERM | GENL_CMD_CAP_DO, }, { diff --git a/include/uapi/linux/dpll.h b/include/uapi/linux/dpll.h index 37b438ce8efc4..ab1725a954d74 100644 --- a/include/uapi/linux/dpll.h +++ b/include/uapi/linux/dpll.h @@ -216,6 +216,7 @@ enum dpll_a { DPLL_A_LOCK_STATUS_ERROR, DPLL_A_CLOCK_QUALITY_LEVEL, DPLL_A_PHASE_OFFSET_MONITOR, + DPLL_A_PHASE_OFFSET_AVG_FACTOR, __DPLL_A_MAX, DPLL_A_MAX = (__DPLL_A_MAX - 1) -- 2.49.1