SDHC Internal Buffer
Introduce the internal buffer of SD host controller.
SD has an internal data buffer for data transfer. This buffer can only be accessed indirectly
by the host driver through the 32-bit Buffer Data Port.
Buffer Size
Non UHS-II
The host controller shall have at least 512 bytes buffer. The size of the data buffer is
determined by the setting of the Block Size.
UHS-II
The host controller shall have at least 512 * N_FCU bytes buffer. The size of the data buffer
is determined by the setting of the Block Size and N_FCU field in
the UHS-II Setting.
UHS-II Buffer Size = UHS-II Block Size * N_FCU.