AM2634: SECDED ECC Not being detected without refreshing the memory.

Hi TEMC,

How did you refresh the entire memory? 

I run the ECC test on MSS memory, and all the tests (1-bit and 2-bit ECC error injection) passed without continuously refreshing the memory.

Hi Wang,

In the code that you have used the entire memory is being refreshed (i.e being read and write back) in

ECC_funcTest -> ECC_Example_init ->  SDL_ECC_initMemory(SDL_EXAMPLE_ECC_AGGR, SDL_EXAMPLE_ECC_RAM_ID)

-> SDL_ECC_memoryRefresh((uint32_t *)memConfig.memStartAddr,(size_t)memConfig.size); and also in 

ECC_sdlFuncTest->SDL_ECC_initMemory(SDL_EXAMPLE_ECC_AGGR, SDL_EXAMPLE_ECC_RAM_ID);->SDL_ECC_memoryRefresh((uint32_t *)memConfig.memStartAddr,(size_t)memConfig.size);

In this function the entire bank is being read and write back, If the refresh fn is not being called the ECC test is failing.

Regards,

TEMC

Hi TEMC,

SDL_ECC_memoryRefresh() is required to calculate the ECC value and write the ECC value to ECC space.

Hi Wang,

Can you please explain exactly when the ECC value of memory is updated, Is it updated only when we have refreshed the entire memory?

If so, how is it supposed to protect memory in a real time application where memory is being used for continuous read and writes.

 If not, what is the minimum address blocks from error injecting address that we need to refresh for the SEC/DED error to be detected.

For example, if a bit is corrupted in the memory the SEC error is only raised when the program has manually refreshed the entire memory. otherwise, the error will not be detected by ECC. Is that correct or am i misunderstanding?

Regards,

TEMC

Hi TEMC,

If the ECC is enabled, writing value to memory will calculate and program the ECC to corresponding ECC location. If a bit is corrupted in the memory whose ECC is programmed and enabled, reading this memory location will raise SEC error.

Hi wang,

QJ Wang said:

If the ECC is enabled, writing value to memory will calculate and program the ECC to corresponding ECC location

then why is the ECC not being detected without refreshing the memory even after error injection then writing or reading to that memory,

Hi TEMC,

I will double check tomorrow morning.

Hi Wang,

We are waiting for your response

Hi TEMC,

I reproduced the issue after disabling the refresh.

I am studying the ECC driver in SDL to see if we missed anything in the test case's configuraion. 

Hi Wang,

Thank you for your response,

Kindly let us know whenever there are any new discoveries or updates regarding this issue. 

Regards,

TEMC

I tested the ECC selftest (SEC and DED) without using SDK functions. I have to program the data to the whole bank to make the selftest work. It might be the limitation of the ECC injection only mode.

Need more time to debug it. Thank you for your patience. 

Hi Wang,

Update us when there are any new updates/developments/conclusions regarding this issue.

I will keep you updated.

Hi Wang,

Are there any updates regarding this issue?

Hi TEMC,

I have asked SDK SBL expert to run the ECC selfttest on MSS-L2 (TCMA and TCMB work fine in my test), and I haven't got feedback yet.

Hi Wang,

QJ Wang said:

TCMA and TCMB work fine in my test

Even Without refreshing are they working fine?

QJ Wang said:

I haven't got feedback yet.

Could you please follow up with the SDK SBL expert?

TEMC said:

Even Without refreshing are they working fine?

Yes, have you tried ECC selftest on TCMA and TCMB?

Yes, we have tried ECC self test on TCMA and TCMB but we haven't tried without refreshing the memory. Currently we are not using TCM so our main concern is with L2 RAM.

Got it. I will push our SDL expert to double check the ECC selfttest on MSS-L2.