XB200 unnecessary error thrown

[ratzrattillo]

I noticed that when using the XB-200 expansion board and setting the frequency always the following error will be thrown:

[ERROR @ host/libraries/libbladeRF/src/board/bladerf1/bladerf1.c:2398]
Consider supplying the quick_tune parameter to bladerf_schedule_retune() when the XB-200 is enabled.

This is due to the function bladerf1_set_frequency always calling schedule_retune with NULL as the quicktune parameter, when the tuning mode is BLADERF_TUNING_MODE_FPGA:
https://github.com/Nuand/bladeRF/blob/master/host/libraries/libbladeRF/src/board/bladerf1/bladerf1.c#L2069

The function bladerf1_schedule_retune always checks, if the quicktune parameter is NULL, and throws the error above, if the XB-200 is attached.

Thus, the error can never be avoided, because as soon as calling set_frequency with an XB-200 attached, the error will be thrown.

I propose to get the quicktune parameters and supplying them before calling schedule_retune, when the XB-200 is attached.

This could be a solution replacing line 2069 in bladerf1.c:

if (attached == BLADERF_XB_200) {
    bladerf_quick_tune qt;
    status = bladerf_get_quick_tune(dev, ch, &qt);
    if (status != 0) {
        return status;
    }
    status = dev->board->schedule_retune(dev, ch, BLADERF_RETUNE_NOW, 0, &qt);
}
else {
    status = dev->board->schedule_retune(dev, ch, BLADERF_RETUNE_NOW, frequency, NULL);
}

What do you think? Looking forward to your feedback!

Another idea would be to stop throwing this error and rather printing it as INFO, to remind the programmer of setting the frequency with the quicktune parameters, leading to an example page like e.g.: https://nuand.com/libbladeRF-doc/v2.2.1/tuning.html

[ratzrattillo]

Added a pull request: #883

[rthomp10]

I believe changing the log message to INFO serving as a reminder is the right way to go. The issue will be fixed in the next release.