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CSI_VERT_DOWNSIZE_EN causes loss of vsync

Question asked by Miki Grof-Tisza on Apr 12, 2016
Latest reply on Apr 14, 2016 by Joan Xie

I'm working on a custom imx6qp board, and in an effort to reduce the bandwidth from CSI->SMFC->IDMAC->MEM, I'm trying to downsize in the CSI.  If I enable the bit CSI_VERT_DOWNSIZE_EN, then vsync is lost.  I'm using IPU_CSI_CLK_MODE_CCIR1120_PROGRESSIVE_SDR mode.  It works fine with the downsize disabled, but with it enabled the frame rolls continuously.  Also it appears to only see half the frames.  I'm testing with 1080p30 coming in, but if I count the frames with the downsize enabled, then the framerate is exactly half of the expected 30fps.

Any ideas what else needs to be tweaked to accommodate this change?

I've set the IDMAC vertical dimension to 1/2 the actual, so the frame looks otherwise correct.

 

Thanks,

Miki

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