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LS1043A hard-coded RCW questions

Question asked by Alexander Mikhailov on Jul 28, 2016
Latest reply on Jul 28, 2016 by Adrian Stoica


We are developing a board with LS1043A and planning to use eMMC to boot from (including storing RCW).

Do we even need to provide a hard-coded RCW source to the configuration pins on startup if we plan to use JTAG to bring up the board? If not, and JTAG can load any RCW to a blank CPU, what is the whole point of hard-coded RCW?

At first i thought we have to provide a hard-coded RCW source to the pins to be able to flash the eMMC with JTAG but since then i have seen notices of JTAG being able to load any RCW regardless.

Then if we do have to use hard-coded RCW at board bring-up, the Reference Manual says "The hard-coded RCW option should be selected based on the system SYSCLK and DDRCLK frequency combination." but "If a hard-coded RCW option is used, the user should not enable the core and the DDR controllers". How do I do anything without enabling the core? Also, do I need DDRCLK in hard-coded mode? The problem is, we plan to use a differential SYSCLK as a reference clock for DDR but the hard-coded register values set it up so that DDR has an independent source. Again, I assume it can be configured with the software during bring-up process?


To summarize the question - what are the situations when hard-coded RCW provide useful? And can I safely assume that I will be able to switch to a single-source clock at some point afterwards without having to provide an independent DDR clock at first?