Hom/Sam Change Outside Of Reset; St3-Hom_P Bit (Bit 8); St3-Hom_R Bit (Bit 9) - Texas Instruments OMAP5912 Reference Manual

MPU Interface
5.1

HOM/SAM Change Outside of Reset

5.2 ST3—HOM_P Bit (Bit 8)
5.3 ST3—HOM_R Bit (Bit 9)
56 DSP Subsystem
Only the DSP can invoke a HOM/SAM change outside of reset. The mode
change is initiated by a DSP write to HOM_P bit (bit 8) and HOM_R bit (bit 9)
of the ST3 register. The appropriate bit is written to request the
SAM_M/HOM_M or SAM_P/HOM_P change. The mode change is not
reflected on bits 8 and 9 in ST3 until the internal controller completes the mode
switch. Therefore, the DSP polls bits 8 and 9 after requesting a mode change
to ensure that the mode change is complete.
The HOM_M/SAM_M and HOM_R/SAM_R status can be observed by the
MPU by reading the MPU_DSP_Status_Register.
The host-only mode for peripherals (HOM_P bit) determines whether the
peripherals are owned only by the MPU or shared by the MPU and the DSP:
-
0: Off
Peripherals are shared by the MPU and the DSP. If you clear the HOM_P
bit, a request for sharing is sent to the peripheral domain controller. If the
peripheral domain controller clears the HOM_P bit, the clearing indicates
that the MPU no longer has exclusive ownership of the peripherals.
-
1: On
Peripherals are owned only by the MPU. If you set the HOM_P bit, a re-
quest for HOM is sent to the peripheral domain controller. If the peripheral
domain controller sets the HOM_P bit, the setting indicates that the MPU
has exclusive ownership of the peripherals.
The MPUI RAM is the portion of the DSP RAM that is accessible by the MPUI.
The HOM_R bit determines/shows whether the MPUI RAM is owned only by
the MPUI or shared by the host processor and the C55x DSP:
-
0: Off
The MPUI RAM is shared by the host processor and the DSP. If you clear
the HOM_R bit, a request for sharing is sent to the MPUI. If the MPUI
clears the HOM_R bit, the clearing indicates that the MPU no longer has
exclusive ownership of the MPU RAM.
SPRU750A