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diff --git a/doc/README.mpc8349emds.ddrecc b/doc/README.mpc8349emds.ddrecc index d8edada..401c0b6 100644 --- a/doc/README.mpc8349emds.ddrecc +++ b/doc/README.mpc8349emds.ddrecc @@ -1,3 +1,24 @@ +Overview +======== + +The overall usage pattern for ECC diagnostic commands is the following: + + * (injecting errors is initially disabled) + + * define inject mask (which tells the DDR controller what type of errors + we'll be injecting: single/multiple bit etc.) + + * enable injecting errors - from now on the controller injects errors as + indicated in the inject mask + +IMPORTANT NOTICE: enabling injecting multiple-bit errors is potentially +dangerous as such errors are NOT corrected by the controller. Therefore caution +should be taken when enabling the injection of multiple-bit errors: it is only +safe when used on a carefully selected memory area and used under control of +the 'ecc test' command (see example 'Injecting Multiple-Bit Errors' below). In +particular, when you simply set the multiple-bit errors in inject mask and +enable injection, U-Boot is very likely to hang quickly as the errors will be +injected when it accesses its code, data etc. Use cases for DDR 'ecc' command: |