SPRUJ28E November 2021 – September 2024 AM68 , AM68A , TDA4AL-Q1 , TDA4VE-Q1 , TDA4VL-Q1
Several DPHY timing constraints must be respected by the system, which are described in this section. When a switch in ULP is requested, the application should be aware that the D-PHY needs 1 ms to leave this state (this timing is guaranteed by the DSI itself). It makes no sense to start an ULP request if the expected time in ULP is short.
When PLL power down is asserted, the system should continue to assert for a specific minimum period of time (PLL internal requirement – please refer to DPHY documentation). Please note that shutting down the PLL implies that no clock is present on tx_byte_hs_clk input and thus the DSI link is stopped; even if the system-side interface clocks remain active, no more HS transfers can be done.
Force_stop, ppi_c_force_tx_stop (clock lane) and ppi_d_force_tx_stop (1 per data lane), can be useful to resolve certain deadlock situations, for example: DSI slave does not give back control to master, or critical DPHY error. When a 'force stop mode' is issued by the application, the system should maintain this state on the bus to ensure the request is correctly considered by the D-PHY cells and the stop_state is asserted and direction signal is deasserted.
reg_wait_burst_time (for the LML) must be programmed to ensure that two HS bursts are separated by at least 100 ns. The value will be based on the period of the tx_byte_clk cycle.
VCA: When trying to interleave commands to video stream, it is assumed that only write/read commands and BTA request are sent (no TE). The reason is that such transfers are slow and difficult to predict in term of duration. They could take longer than the slots available for video. The read commands are unpredictable and may cause some break in the video stream, however, they can still be used, if an appropriate response time can be guaranteed. It is the responsibility of the system integrator and the application to plan and implement recovery procedures when the video stream is stalled due to a read that takes too long.