Re: Looking for help to enable eDP1 port on Minnowboard derivative board

Stephano Cetola

A couple of questions:

1. Have you updated the Video BIOS Table (VBT) adding the LVDS details
(dot clock, EDID support, etc)?
2. If so, have you followed the DDI1_XXX lines (at the bridge and LVDS
display), and are the signals present?


On Mon, Jun 3, 2019 at 6:03 PM <rksaripalli@...> wrote:

To all,
I have a board designed on the e3800 SoC. We are reusing the Minnowboard UEFI FW (with some minor changes for the memory controller) and are able to boot this board with the UEFI FW that we are building with these patches.

The board has eDP1 enabled. On this port, we have an integrated LVDS panel using a eDP to LVDS bridge.
a)So essentially, we have DDI1_XXX signals connected to the eDP to LVDS bridge. The bridge translates from eDP to LVDS.
b) The DDI1_DDCDATA and DDI1_DDCCLK are connected directly to i2c on the LVDS panel (for EDID/EEPROM access)
c) On the Minnowboard the eDP1 graphics output port is removed (In the Minnowboard schematics refer to the CPU-DDI/VGA sheet and on the right you will see BayTrail-M remove eDP port)
d) On the DDI0 signals, we have HDMI output.

But with the Minnowboard FW, we are only able to see the display output on HDMI connected through eDP0.
We do not see see any output on eDP1.

Thinking this could be a backlight issue, I even wrote some code to program the DDI_BKLTEN / DDI_BKLTVDD signals (that are tied to GPIO signals in the NC) and that does not work either.

What are the steps/tools I need to do to enable LVDS panel on eDP1?.

Ideally, we would like to have the output be sent to both HDMI and LVDS panel.
I am familiar with UEFI code and I can make any changes needed in the UEFI FW code.
The HDMI is purely for developer support at this point.


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