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Sharing I2C GPIO outputs

Question asked by StevenB on Feb 18, 2014
Latest reply on Feb 20, 2014 by StevenB

I'm trying to combine the zc702/adv7511 HDMI reference design with another design (the Xilinx ZVIK demo which drives the ON Semiconductor image sensor - XAPP 794).  I've stripped out the HDMI output part of the Xilinx demo, and am just using the camera input.  It appears that both designs use the GPIO output on the ZC702 I2C controller, and conflict with each other.  The camera's enable pin is connected to the GPIO, and it gets turned off every few seconds.

 

My guess is that something in the kernel driver writes to the GPIO register every few seconds in some kind of polling operation.  However, after looking at the adv7511 driver source (drivers/gpu/drm/i2c) and inserting some debug statements, it wasn't obvious whether and where this was occurring.  Also, I didn't see anything in the HDMI reference hardware design that indicated that the GPIO pins are connected to anything.

 

Does the HDMI design require the I2C GPIO outputs?  If so, is there documentation somewhere about how this works?  If not, is there something in the driver that I need to modify so that it doesn't overwrite the GPIO register and turn off the camera?

 

Thanks!

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