Hi Rick,
Thank you for quick reply. It almost solved my doubt. CPH and CPL of DRV8320 are corresponding to CP1 and CP2, rather than BST_x of DRV8302, from which I also measured similar waveforms before. ;)
Although the shape of the waveforms is normal, the amplitude of CPH seems to exceed the allowable value that listed in the datasheet, because it is measured about 17V higher than VM (30V) at the max point, while the datasheet tells 13.5V is the absolute maximun.
Is it normal, still?