A data storage device may include a non-volatile memory and a controller. According to a first aspect, a bit error rate (BER) estimate may be determined at a memory interface of the controller based on hard bit data from the non-volatile memory. The BER estimate may be used to determine, prior to transfer of the hard bit data to an error correction coding (ECC) decoder of the controller, whether to request transfer of soft bit data from the non-volatile memory. According to a second aspect, the ECC decoder may be instructed to initiate decoding of a codeword or sub code using a particular operating mode based on the BER estimate for the codeword or sub code. According to a third aspect, sub codes of an ECC codeword may be reordered based on BER estimates for the sub codes, and the reordered sub codes may be provided to the ECC decoder.