ADSP-SC57x/2157x series processors have two PCGs, PCG A and PCG B. There is one major difference between PCG's of ADSP-SC58x series processor and ADSP-SC57x series processors.
When CLKIN is chosen as the source of Clock in PCGs of ADSP-SC58x series processors, SYS_CLKIN0 will be used by PCG A ,PCG B and SYS_CLKIN1 will be used by PCG C ,PCG D by default. But in ADSP-SC57x series processors, this is programmable. When CLKIN is chosen as source of clock for PCG A or PCG B in ADSP-SC57x series processors, CLKINSEL field decides CLKIN source.Please go through Hardware reference manual for more details.