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Visitor aawce
Visitor
1,273 Views
Registered: ‎09-13-2018

DSI MIPI in-band commands not working

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Hi,

 

We would appreciate any advice/support on in-band MIPI command problem.

 

We are using DSI controller to driver a MIPI display that only supports configuration through in-band MIPI commands, i.e. using a DCS Short Write 0-parameter or DCS Short Write 1-parameter to write configuration registers in the display.

 

The mfg has given us a sequence of config commands to bring up the display(attached), but it does not work (display comes up in gray screen). However, if we write just to page 0 (the default page on power up) using our dcs_short_0()  or dcs_short_1(), it will come up with our colorbar testimage, although it looks poor obviously because we haven't written the configuration data into the other pages. We can also use our dcs_short commands to put the display to sleep, etc. which are avail in page0.  So essentially our dcs functions are working (note: these functions write to the DSI core's command queue appropriately to implement DCS Short Write 0-param or DCS Short Write 1-param).

 

So it appears the change-page command sequence does not work.  Here's the sequence to change to page 1:

dcs_short_0(0xFF); dcs_short_0(0xFF); dcs_short_0(0x98); dcs_short_0(0x06); dcs_short_0(0x04); dcs_short_0(0x01);

 

We have tried different combinations of dcs_short_0() or dcs_short_1() which doesn't seem to make a difference.  The mfg says that dcs-short0 is all that's needed and that's what they use.  And they don't seem to understand why it's not working.

 

Also attached are all our timing parameters for the DSI core, and below is how the display controller describes the page-change command.

 

Appreciate any ideas on what's wrong,  how to debug this, or experiments to try, etc.

Thks,

Chris

 

awy480800T40-page-change-cmd-diagram.png

 

dispctrl-pagechange.png

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1 Solution

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Xilinx Employee
Xilinx Employee
1,226 Views
Registered: ‎03-30-2016

Re: DSI MIPI in-band commands not working

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Hello Chris @aawce

 

2. I disagree.

    If a DCS Command requires more than one parameter, the command shall be sent as a Long Packet type DCS.
    See the picture below. A short packet only contains 4 byte, very different compared to Figure 22.

           (ID=0x05 , Data 0, 0x00,   ECC).

           (ID=0x15 , Data 0, Data 1, ECC).

    We must put correct Command code into Data0, or else Display will not recognize it as DCS command.

    Please see MIPI DCS specification for detailed Command list.

 

1. Unfortunately, this limitation is in Xilinx MIPI DSI-TX IP.

    MIPI DSI spec mentioned that as a host processor, we can choose what mode we can support.
    Xilinx IP only implemented IP to support Type 4 architecture, this is the reason we do not support DCS long write.

 

Did you contact your FAE on this issue ?

 

Kind regards

Leo

 

--BTW, I did not understand with " DSI to stay in ULP mode and never go into HS mode."

Could you please share your finding ? Some Oscilloscope screenshots may help me to understand he situation here.

 

 

XF_1011_CHRIS_PACKET_STRUCT.png
XF_1011_CHRIS_TYPE4.png
8 Replies
Xilinx Employee
Xilinx Employee
1,255 Views
Registered: ‎03-30-2016

Re: DSI MIPI in-band commands not working

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Hello Chris @aawce

 

1. Could you please check our PG238 IP Fact ?

    It mentioned that Xilinx MIPI DSI Subsystem IP implements a DSI transmit interface in adherence to the MIPI DSI standard v1.3 (Type 4 architecture). Basically Type4 operates in Video mode only, but our MIPI DSI IP also supported some DCS short write command as mentioned on PG238 Table 2-11.

 

2. Regarding your Display configuration.

It seems you will need to use DCS long write command to do the job, but unfortunately this is not supported by Xilinx MIPI DSI TX SS, right now.

 

3. We cannot send DCS long write command, using a sequential of DCS short write commands. (The packet structure is different, so Display will not be able to able to response )

dcs_short_0(0xFF); dcs_short_0(0xFF); dcs_short_0(0x98); dcs_short_0(0x06); dcs_short_0(0x04); dcs_short_0(0x01);

 

There is no work around for this, without doing MIPI DSI TX IP enhancement.

@chrisar,  
Could you please help to give Chris a solution. We need to involve Marketing for a solution.

 

 

Thanks & regards

Leo

XF_PG_DSI_TYPE4_ONLY.png
XF_ARC_SPEC_DSI.png
Visitor aawce
Visitor
1,244 Views
Registered: ‎09-13-2018

Re: DSI MIPI in-band commands not working

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Hi Leo,

Thanks much for quick response.

 

On your 2nd point - the display mfg says the page-change command, even though it has 6-parameters, can be sent out using dcs_short_0().  At least that's what they claim.  When looking at the spec - do you disagree?

 

On the your 1st point - do you mean I should check with mfg to see if they are using MIPI DSI standard v1.3, Type 4 architecture, (video mode only)?   I will ask them as it's not in their datasheet.  FYI - I include the display controller datasheet used on the display in case you have more ideas.

 

THks,

CHris

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Visitor aawce
Visitor
1,235 Views
Registered: ‎09-13-2018

Re: DSI MIPI in-band commands not working

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Hi Leo,

 

I also confirmed with mfg that display controller supports the following:

 

Supports DSI version 1.02.00
Supports D-PHY version 1.00.00
Supports DCS version 1.02.00

Shouldn't this be compatible with the XLNX DSI using v1.3 ?

 

Also I have just noticed that now the MIPI lanes appear to be always stay in ULP mode as I only see .8V signaling at 20Mb/s (the escape clock setting of D-PHY).  So we are now looking into the cause of that.  We are using XLNX test image generator as input to the DSI core and have confirmed with ILAs that it is operating correctly with colorbar, etc. into the DSI core, and the input stream timings look correct.

 

Much appreciated if you have any suggestions/pointers as to what would cause DSI to stay in ULP mode and never go into HS mode.

 

Thks,

Chris

 

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Xilinx Employee
Xilinx Employee
1,227 Views
Registered: ‎03-30-2016

Re: DSI MIPI in-band commands not working

Jump to solution

Hello Chris @aawce

 

2. I disagree.

    If a DCS Command requires more than one parameter, the command shall be sent as a Long Packet type DCS.
    See the picture below. A short packet only contains 4 byte, very different compared to Figure 22.

           (ID=0x05 , Data 0, 0x00,   ECC).

           (ID=0x15 , Data 0, Data 1, ECC).

    We must put correct Command code into Data0, or else Display will not recognize it as DCS command.

    Please see MIPI DCS specification for detailed Command list.

 

1. Unfortunately, this limitation is in Xilinx MIPI DSI-TX IP.

    MIPI DSI spec mentioned that as a host processor, we can choose what mode we can support.
    Xilinx IP only implemented IP to support Type 4 architecture, this is the reason we do not support DCS long write.

 

Did you contact your FAE on this issue ?

 

Kind regards

Leo

 

--BTW, I did not understand with " DSI to stay in ULP mode and never go into HS mode."

Could you please share your finding ? Some Oscilloscope screenshots may help me to understand he situation here.

 

 

XF_1011_CHRIS_PACKET_STRUCT.png
XF_1011_CHRIS_TYPE4.png
Moderator
Moderator
1,159 Views
Registered: ‎11-09-2015

Re: DSI MIPI in-band commands not working

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HI @aawce,

 

Did the reply from @karnanl answered your question?

 

If your question is answered or your issue is solved, please kindly mark the response which helped as solution (click on "Accept as solution" button below the reply)

If this is not solved/answered, please reply in the topic giving more information on your current status.

Thanks and Regards,


Florent
Product Application Engineer - Xilinx Technical Support EMEA
**~ Don't forget to reply, give kudos, and accept as solution.~**
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Xilinx Employee
Xilinx Employee
1,143 Views
Registered: ‎03-30-2016

Re: DSI MIPI in-band commands not working

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Hello Florent

I am having conversation related to this topic with @aawce  and @chrisar .

 

Chris can solve this issue, since the display company has programmed the display to support short writes only.

But we still see unexpected behavior with DSI TX set to 350Mbps, as mentioned below :

https://forums.xilinx.com/t5/Video/mipi-dsi-tx-core-output-clock-is-incorrect/td-p/899610

 

Thanks & regards

Leo

Observer thomasmurphyge
Observer
1,037 Views
Registered: ‎09-20-2018

Re: DSI MIPI in-band commands not working

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Hello Leo,

I am also considering an application with the Xilinx DSI Tx IP and a display using the ILI9806E and am trying to implement the configuration writes. Do you have more information on using the ILI9806E display controller using only short writes?

 

Thanks,

Thomas

Xilinx Employee
Xilinx Employee
1,013 Views
Registered: ‎03-30-2016

Re: DSI MIPI in-band commands not working

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Hello Thomas @thomasmurphyge , @miker

 

As mentioned in this thread. Currently Xilinx MIPI DSI TX only support DCS short writes.

Could you please contact Display Vendor to provide a workaround for this ?

@aawcedid this to to work-around IP limitation.

 

Thanks & regards

Leo

 

-- Next time, It might be better to post a new thread/question instead of adding to old one.

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