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MIPI DSI HFP stability

Question asked by Mark Vogt on Jun 14, 2020
Latest reply on Jun 16, 2020 by igorpadykov

I have trying to connect a 800x480 RGB TFT to an imx8m mini using a bridge chip.  I have tried 2 different bridge vendors ic's and both show the same issue.  The horizontal front porch is not consistent from line to line.  I am seeing a variation of up to 7x pixel clocks per line.


In the attachment I am triggering on the rising edge of data enable.  The horizontal sync is stable, and you can see this issue in the falling edge of data enable for the previous frame.  


I have tried all MIPI DSI flag combinations in the linux driver without success.  I am currently using Video mode without burst and MIPI_DSI_MODE_VIDEO_SYNC_PULSE.  Adjusting these flags change the jitter, but not remove it.


Is there some setting that I'm missing?