The DISPC supports no-standby mode, force-standby mode, and a single smart-standby mode. The mode is set in the DISPC_SYSCONFIG[13:12] MIDLEMODE bit field. The functional clock is always active if the module is enabled. The L3_MAIN clock can be shut down at any time independently of the status of MStandby.
The conditions of assertion of the MStandby signal are:
- In no-standby mode: MStandby is never asserted.
- In force-standby mode: MStandby is asserted when the module is disabled.
- In smart-standby: In the case of one of the following conditions:
- The GFX pipeline is disabled or enabled and the data fetch is complete for the GFX window, or the GFX pipeline is enabled but the data fetch did not complete and data in the DMA buffer is greater than the high threshold value.
- The VID1 pipeline is disabled or enabled and the data fetch is complete for the VID1 window, or the VID1 pipeline is enabled but the data fetch did not complete and data in the DMA buffer is greater than the high threshold value.
- The VID2 pipeline is disabled or enabled and the data fetch is complete for the VID2 window, or the VID2 pipeline is enabled but the data fetch did not complete and data in the DMA buffer is greater than the high threshold value.
- The VID3 pipeline is disabled or enabled and the data fetch is complete for the VID3 window, or the VID3 pipeline is enabled but the data fetch did not complete and data in the DMA buffer is greater than the high threshold value.
- The WB pipeline is disabled or enabled and the data store to memory is complete for the WB picture, or the WB pipeline is enabled but the data storage did not complete and data in the DMA buffer is lower than the low threshold value.
The MStandby signal asserts whenever all five events have occurred or the DISPC is disabled. While MStandby is asserted, the DISPC does not generate any transaction on the L3_MAIN master port.
The conditions of deassertion of the MStandby signal are:
- In force-standby mode: MStandby is deasserted only when the DISPC is enabled.
- In smart-standby mode: In the case of one of the following conditions:
- The GFX pipeline is enabled but the data fetch did not complete for the GFX window, and the data in the DMA buffer is less than the low threshold value.
- The VID1 pipeline is enabled but the data fetch did not complete for the VID1 window, and the data in the DMA buffer is less than the low threshold value.
- The VID2 pipeline is enabled but the data fetch did not complete for the VID2 window, and the data in the DMA buffer is less than the low threshold value.
- The VID3 pipeline is enabled but the data fetch did not complete for the VID3 window, and the data in the DMA buffer is less than the low threshold value.
- The WB pipeline is enabled but the data store did not complete for the WB picture, and the data in the DMA buffer more than the high threshold value.
Detection of the deassertion conditions assumes that the interface clocks are active.