AD9361 NO-OS driver: BBPLL calibration timeout?

Hi,

I am using AD9361 NO-OS driver (from 2014_R2). I only need to control AD9361 via SPI bus so I use platform_generic.

I compiled the driver and tried on my board. After ad9361_bbpll_set_rate(), I need to wait for long time (~45 seconds) to get "Calibration TIMEOUT (0x5E, 0x80)" error message (see below for the log message).

......

ad9361_bbpll_set_rate: Rate 983040000 Hz Parent Rate 40000000 Hz

Calibration TIMEOUT (0x5E, 0x80)

.......

What may cause this "BBPLL calibration timeout" error?

Thanks,

Allen