README.mpc83xx.ddrecc
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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 testdw' 'ecc testword' 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:
================================
Before executing particular tests reset target board or clear status registers:
=> ecc captureclear
=> ecc errdetectclr all
=> ecc sbecnt 0
Injecting Single-Bit Errors
---------------------------
1. Set 1 bit in Data Path Error Inject Mask
=> ecc injectdatahi 1
2. Run test over some memory region
=> ecc testdw 200000 10
3. Check ECC status
=> ecc status
...
Memory Data Path Error Injection Mask High/Low: 00000001 00000000
...
Memory Single-Bit Error Management (0..255):
Single-Bit Error Threshold: 255
Single Bit Error Counter: 16
...
Memory Error Detect:
Multiple Memory Errors: 0
Multiple-Bit Error: 0
Single-Bit Error: 0
...
16 errors were generated, Single-Bit Error flag was not set as Single Bit Error
Counter did not reach Single-Bit Error Threshold.
4. Make sure used memory region got re-initialized with 0x0123456789abcdef
=> md 200000
00200000: 01234567 89abcdef 01234567 89abcdef .#Eg.....#Eg....
00200010: 01234567 89abcdef 01234567 89abcdef .#Eg.....#Eg....
00200020: 01234567 89abcdef 01234567 89abcdef .#Eg.....#Eg....
00200030: 01234567 89abcdef 01234567 89abcdef .#Eg.....#Eg....
00200040: 01234567 89abcdef 01234567 89abcdef .#Eg.....#Eg....
00200050: 01234567 89abcdef 01234567 89abcdef .#Eg.....#Eg....
00200060: 01234567 89abcdef 01234567 89abcdef .#Eg.....#Eg....
00200070: 01234567 89abcdef 01234567 89abcdef .#Eg.....#Eg....
00200080: deadbeef deadbeef deadbeef deadbeef ................
00200090: deadbeef deadbeef deadbeef deadbeef ................
Injecting Multiple-Bit Errors
-----------------------------
1. Set more than 1 bit in Data Path Error Inject Mask
=> ecc injectdatahi 1
=> ecc injectdatalo 1
2. Run test over some memory region
=> ecc testword 200000 1
3. Check ECC status
=> ecc status
...
Memory Data Path Error Injection Mask High/Low: 00000001 00000001
...
Memory Error Detect:
Multiple Memory Errors: 0
Multiple-Bit Error: 1
Single-Bit Error: 0
...
The Multiple Memory Errors flags not set and Multiple-Bit Error flags are set.
4. Make sure used memory region got re-initialized with 0x0123456789abcdef
=> md 200000
00200000: 01234567 89abcdef 01234567 89abcdef .#Eg.....#Eg....
00200010: 01234567 89abcdef 01234567 89abcdef .#Eg.....#Eg....
00200020: 01234567 89abcdef 01234567 89abcdef .#Eg.....#Eg....
00200030: 01234567 89abcdef 01234567 89abcdef .#Eg.....#Eg....
00200040: 01234567 89abcdef 01234567 89abcdef .#Eg.....#Eg....
00200050: 01234567 89abcdef 01234567 89abcdef .#Eg.....#Eg....
00200060: 01234567 89abcdef 01234567 89abcdef .#Eg.....#Eg....
00200070: 01234567 89abcdef 01234567 89abcdef .#Eg.....#Eg....
00200080: deadbeef deadbeef deadbeef deadbeef ................
00200090: deadbeef deadbeef deadbeef deadbeef ................
Test Single-Bit Error Counter and Threshold
-------------------------------------------
1. Set 1 bit in Data Path Error Inject Mask
=> ecc injectdatahi 1
2. Enable error injection
=> ecc inject en
3. Let u-boot run for a with Single-Bit error injection enabled
4. Disable error injection
=> ecc inject dis
4. Check status
=> ecc status
...
Memory Single-Bit Error Management (0..255):
Single-Bit Error Threshold: 255
Single Bit Error Counter: 199
Memory Error Detect:
Multiple Memory Errors: 1
Multiple-Bit Error: 0
Single-Bit Error: 1
...
Observe that Single-Bit Error is 'on' which means that Single-Bit Error Counter
reached Single-Bit Error Threshold. Multiple Memory Errors bit is also 'on', that
is Counter reached Threshold more than one time (it wraps back after reaching
Threshold).