According to MIPI DSI Specification, Generic Short Write with 1 Parameter should be 3 bytes long: DI (0x13) + one parameter + ECC. IMX6 always sends at least 4 bytes, in this case: DI + one parameter + one byte of payload data + ECC. Why is so?
Is there any way to send only 2 or 3 bytes?
The MIPI DSI Host controller module supports short write packets type. The issue you observe most likely depends on the driver implementation.
Have a great day,
Artur