Is it possible to reinitialize the DDR controller on the MPC8548 processor without a hardware reset?

[MarkPalamar]

Hi, I am supporting a custom single board computer based on an MPC8548 processor. The board support package initializes everything at power on reset. We have a requirement to reinitialize the board from a software commanded reset.

On other MPC8548 based boards we would write to the reset control register (offset 0xE_00B0).  However, the board designer has confirmed that the HRESET_REQ signal is not connected to anything that could perform the reset.

So, therefore I am trying to reinitialize everything in software.  I am able to reinitialize the DDR controller while running in flash memory. Unfortunately, this does not work 100% of the time (approximately 1 out of 20 attempts it might get stuck waiting for D_INIT to clear) and the documentation (MPC8548 Reference Manual) partially implies that this can only be done after a reset.

Is it possible to reinitialize the DDR memory controller on the MPC8548 without a hardware reset?

[ufedor]

The following sequence is needed to reconfigure already enabled memory controller:

Set DDR_SDRAM_CFG[MEM_HALT] bit;

Read DDR_SDRAM_CFG register to ensure that MEM_HALT has been set;

Clear DDR_SDRAM_CFG[MEM_EN] bit;

Make configuration changes (if needed);

Set DDR_SDRAM_CFG[MEM_EN] bit;

Clear DDR_SDRAM_CFG[MEM_HALT] bit.