SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
The eMMC/SD/SDIOi host controller supports CE-ATA features, in particular the detection of the command completion token. When a command that requires a CCS (the MMCHS_CON[12] CEATA bit is set to 1 and the MMCHS_CMD[3:2] ACEN bit field is set to 0x1) is launched, the host system is no longer allowed to emit a new command in parallel to the data transfer unless it is a command completion disable token.
The settings to emit a command completion disable token are:
When a command completion disable token was emitted (that is, the MMCHS_STAT[0] CC bit is received), the host system is again allowed to emit another type of command (for example, a CMD12 to abort transfer).
A critical case can be encountered when CCSD is emitted during the last data block transfer, and the sequence on the command line is sent close to the CCS token sent by the card.
Three possible cases are:
An interrupt CIRQ is generated when CCS is detected, CCSD is transmitted to the card, and then an interrupt CC is generated when CCSD ends. In this case, the card considers the CCSD sequence.
The CCS bit cannot be detected (conflict is not possible because they drive the same level on the command line, and no CIRQ interrupt is generated; a CC interrupt is generated when CCSD ends).
Only the interrupt CIRQ is generated when CCS is detected.