AnsweredAssumed Answered

Streaming over HDMI and LCD0

Question asked by Pankaj Dhule on Nov 2, 2015
Latest reply on Dec 9, 2015 by Joan Xie

Hi All,


We have developed a system based on the iMX6 Duallite. We are referring SABREBOARD schematic “SCH-27417.pdf” as a reference.


In our system a camera connected on CSI0 interface captures the video and stream it on HDMI and LCD0 interface. Streaming will happen on only one interface (HDMI or LCD0) at a time.


In one of requirement when user presses a button streaming interface needs to switch from LCD0 to HDMI  or  from HDMI to LCD0.


We are facing issues in following usage scenario:


Consider streaming is on HDMI, when we switch streaming to LCD0 interface from HDMI (HDMI cable is connected), LCD display is working properly but HDMI display is giving error of timing mismatch.


Now again if we switch streaming from LCD0 to HDMI, HDMI display is still gives error. To start HDMI display properly we need to switch off and then switch on the HDMI display.



Following are the observation when I probe the HDMI and LCD0 clocks on DSO:


  1. When video streaming over HDMI , HDMI clock is 148MHz(Approximately), No clock at LCD 0 interface clock, Good streaming over HDMI port.-NO ISSUE
  2. When video streaming over LCD 0 port , LCD 0 clock 74MHz (1080P30) and HDMI clock also becomes 74MHz, No streaming seen on HDMI, but good video streaming on LCD 0 port.
  3. When we again switch back to HDMI from LCD0, LCD0 clock becomes zero but HDMI clock is still 74MHz, if we unplug the HDMI cable and plug it again, video Streaming resume over HDMI.


Some more observations:


  • IPU is generating mxc_ipu mxc_ipu: IPU warning  - IPU_INT_STAT_10 = 0x00080000 due to this warning performance has been degraded from 30 fps to 25 FPS for 1080P resolution.
  • Latency has been increased from 200 msec to 400 msec.
  • Error interrupt has been disabled in IPU driver but still getting poor performance(25 fps and ~300- 400 msec latency)
  • Description of IPU_INT_STAT_10 = 0x00080000


Please help us to resolve this issue.