What means the Msp in HAL_MspInit ?
MSPs are user callback functions to perform system level initializations such as (Clock, GPIOs, DMA, interrupts).
The peripheral initialization is done through HAL_PPP_Init() while the hardware resources
initialization used by a peripheral (PPP) is performed during this initialization by calling
MSP callback function HAL_PPP_MspInit().
The MspInit callback performs the low-level initialization related to the different additional
hardware resources: RCC, GPIO, NVIC and DMA.
source:UM1725