[PATCH v2 v2 2/8] mmc: sdhci: add quirk to enable CMD23 for multi-block transfers

[Peng Fan]

On Mon, Jun 29, 2026 at 11:51:16PM +0800, Eric Chung wrote:
>Introduce a controller-specific quirk to select CMD23 (SET_BLOCK_COUNT)
>for read/write multi-block operations instead of the legacy CMD18/CMD25
>with open-ended or pre-defined block counts.
>
>This allows SDHCI host controllers that support CMD23 to improve I/O
>efficiency by reducing the number of CMD12 (STOP_TRANSMISSION) commands
>for multi-block transfers.

This is a misuse of the quirk mechanism.

CMD23 (SET_BLOCK_COUNT) is part of the SD/eMMC specification -
it's the standard defined-length multi-block transfer method.

Quirks exist for hardware that deviates from spec, not for enabling
spec-compliant behavior.

Regards
Peng