iMX8X MIPI DSI Burst mode

[emanuele79]

I'm using IMX8X DSI output with Lontium lt8912. Lontium do not support burst mode, and the mainline driver do not set the relevant flag (correctly) when he call mipi_dsi_attach function.

But HDMI output (from Lontium) works only if I set burst mode on the iMX8X DSI output and this sounds strange.

Is there the possibility that the VIDEO_MODE register definition on iMX8X datasheet is not correct?

Thank you.

Emanuele

[Sanket_Parekh]

Hello @emanuele79,

I hope you are doing well.

->The possibility that the VIDEO_MODE register definition on the iMX8X datasheet is not correct is low.

->Please make sure to check with different DMI/DSI output devices it may be problematic.
->Please make sure to check using different versions of the driver/ kernel version, which is recommended as it offers the latest driver/fw to use.

It may be helpful.

Thanks & Regards,
Sanket Parekh

[arturobuzarra]

Hi @Sanket_Parekh ,

We are facing a similar issue than reported by @emanuele79 with i.MX8QXP and Lontium LT8912B MIPI-DSI to HDMI bridge using your latest BSP "lf-6.6.36-2.1.0".

We are using the upstream driver from drivers/gpu/drm/bridge/lontium-lt8912b.c and according to the Lontium datasheet, LT8912B supports only Non-Burst mode video operation with Sync Events and continuous clock on clock lane. The i.MX8QXP platform does not work using the default Non-Burst mode with Sync Events however forcing to use the Burst mode it is working fine.

We already tested the same upstream driver with the default Non-Burst mode video operation with Sync Events on a i.MX93 and works fine, so it points that there is something wrong with the MIPI-DSI driver that uses the i.MX8QXP platform, "Northwest Logic MIPI DSI Host controller" (CONFIG_DRM_NWL_MIPI_DSI) located in drivers/gpu/drm/bridge/nwl-dsi.c.

Could you help to us to identify the root cause of that issue?

Thanks in advance,

Arturo.