On 10. 09. 25 2:34 odp., Vadim Fedorenko wrote:
On 10.09.2025 11:32, 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@xxxxxxxxxxxxx>
Signed-off-by: Ivan Vecera <ivecera@xxxxxxxxxx>
[...]
+static int
+zl3073x_devlink_param_phase_avg_factor_set(struct devlink *devlink,
u32 id,
+ struct devlink_param_gset_ctx *ctx,
+ struct netlink_ext_ack *extack)
+{
+ struct zl3073x_dev *zldev = devlink_priv(devlink);
+ u8 avg_factor, dpll_meas_ctrl;
+ int rc;
+
+ /* Read DPLL phase measurement control register */
+ rc = zl3073x_read_u8(zldev, ZL_REG_DPLL_MEAS_CTRL, &dpll_meas_ctrl);
+ if (rc)
+ return rc;
+
+ /* Convert requested factor to register value */
+ if (ctx->val.vu8 < 15)
+ avg_factor = ctx->val.vu8 + 1;
+ else
+ avg_factor = 0;
+
This looks like avg_factor = (ctx->val.vu8 + 1) & 0x0f;
The same logic can be applied for get() function assuming we are aware of
unsigned roll-over...
Yes, I know about this trick but I wanted to use more readable code and
leave potential optimization to the compiler.
Ivan
