LX2160A second RCW source

[dstepanov]

Hello! I’m using LX2160A clearfog development board and trying to implement reliable boot in case of failure of one of the boot sources (eMMC/SD/SPI).

LX2160A Reference Manual (Rev. 0RH, 07/2020) in detailed Power-On reset description (4.9.5, table 11, stage 13) points that it is possible to use second RCW source

If the Service processor detects that the RCW loading failed, it initiates RCW loading from a second RCW source. If boot fails from the RCW loaded at offset 0 or 0x1000 (in case of SD), the boot ROM searches for RCW at 8 MB (8 MB + 0x1000 for SD) offset on the device.

I’m little bit confused with this description - what really happens if boot fails? where the second RCW source is selected? Does the boot process try to read RCW from first boot source (using 2 offsets) and if these 2 attempts fails it performs another 2 attempts (with 2 different offsets)?

[yipingwang · Accepted solution]

The RM needs to be corrected. There is no second RCW source. This was initially planned but due to certain hardware issues, could not be implemented.

The statement should be removed:
I/O drivers for the backup RCW source are enabled, specifically those pins associated only with the secondary RCW interface.However in LX2160, we do have a provision of secondary RCW source on the same boot device. If boot fails from RCW loaded at offset 0 or 0x1000 ( in case of SD), ROM searches for RCW at 8 MB (8 Mb + 0x1000 for SD) offset on the device.