iMX8QM eDP Support

[prashanthkumar]

Hi,

In iMX8QM custom board with 4.14.98 Kernel BSP, we are trying to configure "eDP" support (1366x768 resolution) using DP(Display Port) signal. But the display is not getting up. Also EDID read for eDP is failing.
With the same setup the DP is working properly for 4K@60fps.

The kernel Device tree content for eDP/DP as follows,
---------------------------------------------------------------------

&hdmi {
compatible = "fsl,imx8qm-dp";
assigned-clocks = <&clk IMX8QM_HDMI_PXL_SEL>,
<&clk IMX8QM_HDMI_PXL_LINK_SEL>,
<&clk IMX8QM_HDMI_PXL_MUX_SEL>;
assigned-clock-parents = <&clk IMX8QM_HDMI_AV_PLL_CLK>,
<&clk IMX8QM_HDMI_AV_PLL_CLK>,
<&clk IMX8QM_HDMI_AV_PLL_CLK>;
dp-lane-mapping = <0x1b>;
dp-link-rate = <0x14>;
dp-num-lanes = <0x4>;
fsl,edp;
status = "okay";
};

The driver for eDP/DP support using is,

drivers/gpu/drm/imx/hdp/imx-hdp.c

drivers/gpu/drm/imx/hdp/imx-dp.c

The eDP Datasheet which we are using is attached for your reference.
Is the above DTS configuration is proper? Kindly do the valuable support to resolve the issue.

Thanks in advance.

Best Regards,

Prashanth Kumar K

[rob_mclean]

@gor_kh 

I know it has been a while since you asked, but since I just went through what you were going through, I decided I would share that I did get my DP panel working.

Varicite supports DP/eDP with their i.MX8QM SOM.  Here is a  link to their reference design carrier board.  Page 7 has the HDMI/DP/eDP circuitry.  Pay attention to the note about swapping HDMI lanes 0 and 2 for DP, and there are various lines with pull up/down and series caps.

Once you are sure you've got the HW right, I used their device tree from here (imx8qm-var-spear-dp.dts) as inspiration for the device tree changes needed to get the panel working.

[igorpadykov]

Hi Prashanth 

unfortunately eDP is not supported in BSP according to Release Notes

from Linux L4.14.98_2.0.0 Documentation

May be suggested to ask additional support through local nxp marketing office.

Best regards
igor
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[gor_kh]

Hello @igorpadykov ,

I would like to know, is there any update in new BSP releases connected with DP support? I looked through all linux release notes, and it seems there is no changes connected with DP. Could you approve that? Or if there are updates regarding DP support for imx8mq, could you send me the link to correct bsp? And what about the firmware?

Best regards,

Gor.