On 2018-08-01 11:35, Russell King - ARM Linux wrote:

On Wed, Aug 01, 2018 at 11:01:12AM +0200, Peter Rosin wrote:

quoted

I don't think it's a problem with the atmel I2C driver. IIRC, the
tda998x driver issues the command a initiate the EDID read, but that
times out. So it appears to be the TDA19988 that fails to read the
EDID over the DDC bus? Which brings me to the double problem with the
scopes mentioned above...

It sounds like it.

It may be helpful to know that there are HDMI pass-through boards
available that give access to all the HDMI signals:

https://elabbay.myshopify.com/collections/camera
https://elabbay.myshopify.com/collections/camera/products/hdmi-af-af-v1a-hdmi-type-a-female-to-hdmi-type-a-male-pass-through-adapter-breakout-board

I've never bought from them, so please don't take this as a
recommendation - the fact that there seems to be no company details
on their site doesn't seem good, and as the whois for elabbay.com is
obscured also doesn't give me any confidence to buy from them.

I still will not be able to inspect the DDC bus between the TDA19988
and the buffer circuit (IP4786), but the gadget seems useful enough and
it's not a shitload of money. We'll see how long it takes for it to get
here...

Thanks for the pointer! Maybe :-)

Cheers,
Peter