mcasp clock on BeagleBone Black for PCM3168

Hi…
I want to interface a PCM3168 codec to the bleaglebone black, but i don’t know if the SCKI of the codec shoul be connected to mcasp0_ahclkr or the mcasp0_ahclkx, or if the trhee of them sould be driven externally with a PLL or something…

I’ve already looked up in datasheets of arm3358, PCM3168, beaglebone black, etc… but i can’t find an answer… or i’m to dumb to look for it…

I would prefer to get the SCKI from the mcasp pins, in order to get the smallest size of the board i’m designed, and i think i can get it from mcasp0_ahclkr or the mcasp0_ahclkx, but i don’t know if that’s right, and if it is, which one of them choose…

Thanks very much