DRV8323R: Weird GHx waveform

Hi,

I use DRV8323RS to drive PMSM, and the GHx waveform is weird (as shown below).

Does anyone know how it is generated? 

VM: 48V

IDRIVEP_HS: 30mA

IDRIVEN_HS: 60mA

IDRIVEP_LS: 30mA

IDRIVEN_LS: 60mA

DEAD_TIME: 400ns

PWM Control Modes: 3x PWM Mode

MOSFETs: csd19533q5a

YELLOW: GHB, BLUE: INHB