SPRUJ28E November 2021 – September 2024 AM68 , AM68A , TDA4AL-Q1 , TDA4VE-Q1 , TDA4VL-Q1
For 1-bit ECC error, the MSMC2DDR bridge logs the address location for the error in an internal 2-level deep FIFO. It stores the first two 1-bit ECC errors. The DDRSS_ECC_1B_ERR_ADR_LOG_REG register shows the address on top of the internal FIFO. Software should write 0x1 to the DDRSS_ECC_1B_ERR_ADR_LOG_REG[28-0] ECC_1B_ERR_ADR field to pop the FIFO and display the next address stored. The FIFO is loaded with the address for the next 1-bit ECC error if it is not full. If a single address is associated with more than one ECC error, that address is logged twice.
The number of 1-bit ECC errors can be counted using the DDRSS_ECC_1B_ERR_CNT_REG register. The MSMC2DDR bridge also supports programming a threshold in the DDRSS_ECC_1B_ERR_THRSH_REG register. When the 1-bit error count is equal to or greater than the programmed threshold, the bridge sets the DDRSS_V2A_INT_RAW_REG[3] ECC1BERR bit and also triggers the DDR0_DDRSS_DRAM_ECC_CORR_ERR_LVL_0 interrupt. When servicing the interrupt, software needs to clear the error count otherwise further interrupts will not be triggered. For 2-bit ECC errors, the bridge sets the DDRSS_V2A_INT_RAW_REG[4] ECC2BERR bit and also triggers the DDR0_DDRSS_DRAM_ECC_UNCORR_ERR_LVL_0 interrupt. The bridge does not correct the data for these uncorrectable errors. Along with generating the interrupt, the bridge also reports an error to the requesting initiatior and sends all zeros for the data. The bridge also logs the address location for the error in the DDRSS_ECC_2B_ERR_ADR_LOG_REG register.
The MSMC2DDR bridge sets the DDRSS_V2A_INT_RAW_REG[5] ECCM1BERR bit and triggers the DDR0_DDRSS_DRAM_ECC_UNCORR_ERR_LVL_0 interrupt whenever it receives multiple 1-bit errors in different data words of the same SDRAM burst. This is done because the probability of receiving multiple 1-bit errors in different data words of the same SDRAM burst is very low. If this occurs, the chances are that there were multi-bit errors in each data word. Therefore, for reliability, pessimistic approach is taken to report these as a fatal error. The threshold for the number of 1-bit errors that result in an uncorrected error, reporting can be set by writing to the DDRSS_ECC_CTRL_REG[12-8] COR_ECC_THRESH field. For reliability, the threshold is always kept at 0/1 meaning 1-bit error in 2 or more data words is reported as a 2-bit error. For debug, the threshold can be changed to a higher value. Note that since these are multiple 1-bit errors, the statistic logging is done in the DDRSS_ECC_1B_ERR_CNT_REG and DDRSS_ECC_1B_ERR_ADR_LOG_REG registers.