SN65DSI86: SN65DSI86

Lorenzo Veltroni

Part Number: SN65DSI86

Dear TI team,

I would like to ask you regarding a couple of CSR registers, which are not described along nor datasheet neither programming guide.

Those registers are MVID and NVID; it's not clear how the value for those register is defined for a specific application, the meaning of these registers and how the value can change depending on different eDP panels.

In addition, I would like to receive info if a wrong value could infer into eDP communication resulting into a wrong panel image.

During our internal tests we noticed the following registers value when a blank screen has been experienced:

0x40 = 01 ; 0x41 = 00

While a different value when the right picture is showed into the panel:

0x40 = 64 or 69

0x41 = 46

Many thanks for your support.

over 4 years ago

0 David (ASIC) Liu over 4 years ago

TI__Guru**** 177386 points

Hi,

I would refer you to the DisplayPort spec for the detail on MVID (m value for video) and NVID (n value for video). But to debug the blank screen issue, it is better to read the DSI86 status registers 0xF0 to 0xF8.

I put together a FAQ on debugging the blank screen, please see this link: https://e2e.ti.com/support/interface-group/interface/f/interface-forum/945403/faq-sn65dsi86-sn65dsi86-black-screen-debugging-guide

Does the color bar work in this particular case if you enable it?

Thanks

David

0 Lorenzo Veltroni over 4 years ago

Prodigy 110 points

Hi David,

Thanks for your prompt reply.

Yes, when a faulty black screen happens, then if we enable the test pattern the colour bars work.

This is the reason why at first stage we excluded a issue due eDP interface, but we found a mismatch for those registers values from a working condition to a wrong one.

Do you suggest to investigate into 0x40 and 0x41 registers or to focus into status registers 0xF0 to 0xF8?

Many thanks,

Lorenzo

0 Lorenzo Veltroni over 4 years ago in reply to David (ASIC) Liu

Prodigy 110 points

Hi David,

Thanks for your prompt reply.

Yes, when a faulty black screen happens, then if we enable the test pattern the colour bars work.

This is the reason why at first stage we excluded a issue due eDP interface, but we found a mismatch for those registers values from a working condition to a wrong one.

Do you suggest to investigate into 0x40 and 0x41 registers or to focus into status registers 0xF0 to 0xF8?

Many thanks,

Lorenzo

0 David (ASIC) Liu over 4 years ago in reply to Lorenzo Veltroni

TI__Guru**** 177386 points

Lorenzo

If the color bar works, then the eDP side is ok. I would focus on the DSI side. In particular, I would look at register 0xF0, 0xF1, 0xF2, 0xF3, 0xF6, and 0xF7 for any issue with DSI interface.

Thanks

David

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SN65DSI86: SN65DSI86