Our customer tried reading a i.MX7S efuse, and succeeded reading lot number programmed in 0x410[31:0] and 0x420[10:0].
However, 0x420[31:11] was all "0".
According to Table 6-19 of IMX7DRM Rev.0.1, wafer number and X/Y coordinate should be programmed in the field.
They executed the process chapter 184.108.40.206.1 and 220.127.116.11.2, so we think the procedure was not wrong since they could read 0x410[31:0] and 0x420[10:0] correct.
Do think think why 0x420[31:11] cannot be read?