Rick123
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DSI Interface to Non Raspberry Pi Display

Sat Jul 22, 2017 12:23 am

Hi all,
I was told that the DSI interface on all the Raspberri Pis is "closed architecture" (i.e. has some software hack) whereby it only allows the official PI Display to be connected. Is is so?

Most importantly is that the same on the Compute Module? Or the Compute Module being for industrial applications is fully compliant with the standard MIPI-DSI standard allowing any DSI Dispal/IC/product to work with it?

Thanks
Rick

klricks
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Re: DSI Interface to Non Raspberry Pi Display

Sat Jul 22, 2017 2:49 am

Rick123 wrote:Hi all,
I was told that the DSI interface on all the Raspberri Pis is "closed architecture" (i.e. has some software hack) whereby it only allows the official PI Display to be connected. Is is so?
Yes that is true...
Rick123 wrote: Most importantly is that the same on the Compute Module? Or the Compute Module being for industrial applications is fully compliant with the standard MIPI-DSI standard allowing any DSI Dispal/IC/product to work with it?
No the compute module does not support other DSI. See section 9.3 here:
https://www.raspberrypi.org/documentati ... T-V1_0.pdf
Unless specified otherwise my response is based on the latest and fully updated Raspbian Stretch w/ Desktop OS.

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Gavinmc42
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Re: DSI Interface to Non Raspberry Pi Display

Sat Jul 22, 2017 3:37 am

You might want to try a DPi, parallel display.
Uses more GPIO but it is supported.
CM's have more GPIO so that helps.
Most Adafruit DPI LCD's seems to be supported, clones that use the same driver chips should work too.

Support for DPI TFT is in the Kernel.
DSI is used in bigger LCD's and is harder to support.
Hopefully on the RPF roadmap there is more displays than just the 7" LCD which actually uses a DSI to LVDS chip/pcb to convert to the LVDS display.
I'm dancing on Rainbows.
Raspberries are not Apples or Oranges

aBUGSworstnightmare
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Re: DSI Interface to Non Raspberry Pi Display

Sat Jul 22, 2017 12:11 pm

Hi,

using DPI is pretty simple and straight forward. Add a 'bridge' chip of your choice to get the interface you need. I've made my own add-on board using a single channel LVDS transmitter - https://www.raspberrypi.org/forums/view ... 0#p1023780

I'm currently working on a baseboard for CM3 which will feature a dual channel LVDS transmitter for full flexibility.

Too bad that the 4-lane DSI is still not usable...

jamesh
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Re: DSI Interface to Non Raspberry Pi Display

Sat Jul 22, 2017 1:25 pm

Rick123 wrote:Hi all,
I was told that the DSI interface on all the Raspberri Pis is "closed architecture" (i.e. has some software hack) whereby it only allows the official PI Display to be connected. Is is so?

Most importantly is that the same on the Compute Module? Or the Compute Module being for industrial applications is fully compliant with the standard MIPI-DSI standard allowing any DSI Dispal/IC/product to work with it?

Thanks
Rick
I believe it's more of a "the code you need to get at to set up the DSI parameters so the display works" is closed source (on the VC4 GPU), rather than a deliberate hack to stop people using the DSI.

I'll ask Monday if there are plans are for exposing the DSI parameters so you could add any DSI display. This might come out of the new OPenGL video driver code, but not sure.
Principal Software Engineer at Raspberry Pi (Trading) Ltd.
Please direct all questions to the forum, I do not do support via PM.

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Re: DSI Interface to Non Raspberry Pi Display

Sat Jul 22, 2017 5:37 pm

Eric's kernel driver already has code for driving the DSI port, so you should be able to write your own kernel driver for a custom panel if you have the relevant skills. His blog is saying that upstream keep on wanting rework on the drivers - hopefully they'll be happy eventually.

Using the DSI port via the firmware is not going to be an option for panels other than the official one.
Software Engineer at Raspberry Pi Trading. Views expressed are still personal views.
Please don't send PMs asking for support - use the forum.
I'm not interested in doing contracts for bespoke functionality - please don't ask.

Rick123
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Re: DSI Interface to Non Raspberry Pi Display

Sat Jul 22, 2017 6:11 pm

jamesh wrote:
Rick123 wrote:Hi all,
I was told that the DSI interface on all the Raspberri Pis is "closed architecture" (i.e. has some software hack) whereby it only allows the official PI Display to be connected. Is is so?

Most importantly is that the same on the Compute Module? Or the Compute Module being for industrial applications is fully compliant with the standard MIPI-DSI standard allowing any DSI Dispal/IC/product to work with it?

Thanks
Rick
I believe it's more of a "the code you need to get at to set up the DSI parameters so the display works" is closed source (on the VC4 GPU), rather than a deliberate hack to stop people using the DSI.

I'll ask Monday if there are plans are for exposing the DSI parameters so you could add any DSI display. This might come out of the new OPenGL video driver code, but not sure.

Thank you

Rick123
Posts: 53
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Re: DSI Interface to Non Raspberry Pi Display

Sat Jul 22, 2017 6:12 pm

aBUGSworstnightmare wrote:Hi,

using DPI is pretty simple and straight forward. Add a 'bridge' chip of your choice to get the interface you need. I've made my own add-on board using a single channel LVDS transmitter - https://www.raspberrypi.org/forums/view ... 0#p1023780

I'm currently working on a baseboard for CM3 which will feature a dual channel LVDS transmitter for full flexibility.

Too bad that the 4-lane DSI is still not usable...
Thank you aBUGSworstnightmare but unfortunately we need many more pins than those that would be left available.

Rick123
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Re: DSI Interface to Non Raspberry Pi Display

Sat Jul 22, 2017 6:23 pm

Yes please let me know although I have seen the reply from 6by9 below.

aBUGSworstnightmare
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Re: DSI Interface to Non Raspberry Pi Display

Fri Jul 28, 2017 10:00 am

Might not be what your're after but what about uisng a Toshiba TC358870XBG on your baseboard to Bridge from HDMI to DSI?
You Need to design your board anyhow, so extra component doesn't matter.
Yes, it's the additional components Price that matters, but doeing as such should allow you to use whatever Display you want to (up to 4 channel DSI).

Rick123
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Re: DSI Interface to Non Raspberry Pi Display

Fri Jul 28, 2017 10:29 am

Thank you aBUGSworstnightmare, nice chip!!
I was looking at the TI's combo solution which uses SN75LVDS83B with the TFP401A. Your suggestion makes it simpler, more universal and lower cost.
Unfortunately we cannot find any stock. On the main distributors. Are you using it on some project? If so which supplier do you use?
Thank

aBUGSworstnightmare
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Re: DSI Interface to Non Raspberry Pi Display

Fri Jul 28, 2017 11:27 am

Have you tried Avnet as well? Possible that all of them have standard lead time.

TFP401A+SN75LVDS83B gives you single channel LVDS Interface (max resolution), and not MIPI DSI.
So, you're free in regards of the display interface to use?
Then you can also think about adding another Transmitter to the TFP401A 48-bit Interface (i.e. for eDP)

Rick123
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Re: DSI Interface to Non Raspberry Pi Display

Fri Jul 28, 2017 11:50 am

because of the DSI restrictions then we had to change to HDMI to LVDS and the TI combo seemed the best solution with available parts.
The Toshiba IC would be ideal but we checked Avnet but it is 12 weeks lead time.

carl0s
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Re: DSI Interface to Non Raspberry Pi Display

Tue May 15, 2018 10:20 pm

I just don't get this.

Unless I'm missing something, you can use any 2-lane MIPI DSI panel you want with an stm32l4+ microcontroller, or stm32f7x9, and probably some others too.They have an lcd tft display controller which provides acceleration too (chrom-art).

What's Broadcom's problem?

aBUGSworstnightmare
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Re: DSI Interface to Non Raspberry Pi Display

Wed May 16, 2018 9:11 am

carl0s wrote: I just don't get this.

Unless I'm missing something, you can use any 2-lane MIPI DSI panel you want with an stm32l4+ microcontroller, or stm32f7x9, and probably some others too.They have an lcd tft display controller which provides acceleration too (chrom-art).

What's Broadcom's problem?
Ask Broadcom! What People here can tell you is "GPU Firmware is closed source".
I agree, it's very unpleasant that we can't connect other DSI displays to RPi, but on the other Hand this would also require lot a resourcesn from the foundation to support. There are always tons of quetsions here where people ask how to connect a random display to RPI, regardless of the Interface type. This will not get better once you can use DSI displays ...

6by9
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Re: DSI Interface to Non Raspberry Pi Display

Wed May 16, 2018 9:48 am

aBUGSworstnightmare wrote:
Wed May 16, 2018 9:11 am
carl0s wrote: I just don't get this.

Unless I'm missing something, you can use any 2-lane MIPI DSI panel you want with an stm32l4+ microcontroller, or stm32f7x9, and probably some others too.They have an lcd tft display controller which provides acceleration too (chrom-art).

What's Broadcom's problem?
Ask Broadcom! What People here can tell you is "GPU Firmware is closed source".
I agree, it's very unpleasant that we can't connect other DSI displays to RPi, but on the other Hand this would also require lot a resourcesn from the foundation to support. There are always tons of quetsions here where people ask how to connect a random display to RPI, regardless of the Interface type. This will not get better once you can use DSI displays ...
There is no problem in using DSI!
Drivers are there for DRM/KMS ie the standard Linux display APIs - https://github.com/raspberrypi/linux/bl ... /vc4_dsi.c.
Yes DRM is different from the DispmanX and MMAL APIs that many Pi apps will use, but it's the way we're trying to head (with shimmed DispmanX and MMAL wrappers to use DRM instead of going via the firmware).
There is documentation for it too (https://github.com/anholt/linux/wiki/Ra ... lay-panels), but you will need some knowledge on how Linux plumbs this stuff together.
aBUGSworstnightmare please stop stating that there are no drivers - it's incorrect and starting to bug me!

The firmware is and will remain closed source due to numerous licencing issues. RPT can't resource adding support for numerous different panels from unknown sources, and from bitter experience trying to expose the setup through a generic framework generally ends in pain.
Software Engineer at Raspberry Pi Trading. Views expressed are still personal views.
Please don't send PMs asking for support - use the forum.
I'm not interested in doing contracts for bespoke functionality - please don't ask.

fruitoftheloom
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Re: DSI Interface to Non Raspberry Pi Display

Wed May 16, 2018 9:53 am

carl0s wrote:
Tue May 15, 2018 10:20 pm
I just don't get this.

Unless I'm missing something, you can use any 2-lane MIPI DSI panel you want with an stm32l4+ microcontroller, or stm32f7x9, and probably some others too.They have an lcd tft display controller which provides acceleration too (chrom-art).

What's Broadcom's problem?

I have no idea why you have resurrected an old Post, but to reiterate what has been stated it is Closed Source.

RPT have obviously signed a NDA to use the Broadcom SoC, so this question should be pointed at Broadcom:

https://www.broadcom.com/how-to-buy/#sales
Adieu

aBUGSworstnightmare
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Re: DSI Interface to Non Raspberry Pi Display

Wed May 16, 2018 1:25 pm

6by9 wrote:
Wed May 16, 2018 9:48 am
aBUGSworstnightmare wrote:
Wed May 16, 2018 9:11 am
carl0s wrote: I just don't get this.

Unless I'm missing something, you can use any 2-lane MIPI DSI panel you want with an stm32l4+ microcontroller, or stm32f7x9, and probably some others too.They have an lcd tft display controller which provides acceleration too (chrom-art).

What's Broadcom's problem?
Ask Broadcom! What People here can tell you is "GPU Firmware is closed source".
I agree, it's very unpleasant that we can't connect other DSI displays to RPi, but on the other Hand this would also require lot a resourcesn from the foundation to support. There are always tons of quetsions here where people ask how to connect a random display to RPI, regardless of the Interface type. This will not get better once you can use DSI displays ...
There is no problem in using DSI!
Drivers are there for DRM/KMS ie the standard Linux display APIs - https://github.com/raspberrypi/linux/bl ... /vc4_dsi.c.
Yes DRM is different from the DispmanX and MMAL APIs that many Pi apps will use, but it's the way we're trying to head (with shimmed DispmanX and MMAL wrappers to use DRM instead of going via the firmware).
There is documentation for it too (https://github.com/anholt/linux/wiki/Ra ... lay-panels), but you will need some knowledge on how Linux plumbs this stuff together.
aBUGSworstnightmare please stop stating that there are no drivers - it's incorrect and starting to bug me!

The firmware is and will remain closed source due to numerous licencing issues. RPT can't resource adding support for numerous different panels from unknown sources, and from bitter experience trying to expose the setup through a generic framework generally ends in pain.
@6by9: Sorry to bother you, but where did I mention about missing drivers? I just said GPU firmware is closed source, so why Iis my statement pi**ing you off and why is it different from yours (aslo in regards of support needed)?

6by9
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Re: DSI Interface to Non Raspberry Pi Display

Wed May 16, 2018 1:36 pm

aBUGSworstnightmare wrote:
Wed May 16, 2018 1:25 pm
6by9 wrote:
Wed May 16, 2018 9:48 am
There is no problem in using DSI!
Drivers are there for DRM/KMS ie the standard Linux display APIs - https://github.com/raspberrypi/linux/bl ... /vc4_dsi.c.
Yes DRM is different from the DispmanX and MMAL APIs that many Pi apps will use, but it's the way we're trying to head (with shimmed DispmanX and MMAL wrappers to use DRM instead of going via the firmware).
There is documentation for it too (https://github.com/anholt/linux/wiki/Ra ... lay-panels), but you will need some knowledge on how Linux plumbs this stuff together.
aBUGSworstnightmare please stop stating that there are no drivers - it's incorrect and starting to bug me!

The firmware is and will remain closed source due to numerous licencing issues. RPT can't resource adding support for numerous different panels from unknown sources, and from bitter experience trying to expose the setup through a generic framework generally ends in pain.
@6by9: Sorry to bother you, but where did I mention about missing drivers? I just said GPU firmware is closed source, so why Iis my statement pi**ing you off and why is it different from yours (aslo in regards of support needed)?
You've stated that it's all closed source - the DRM/KMS drivers are not. Full source code upstreamed.
I agree, it's very unpleasant that we can't connect other DSI displays to RPi,
You can if you understand how to configure the Linux kernel display infrastructure. That does NOT have to come from Broadcom or RPT.

Yesterday viewtopic.php?f=44&t=213625#p1315741
Currently not! DSI is handled by GPU and the code is closed source.
Twaddle. You have open source kernel drivers.

Yes the firmware is closed source, but the DSI interface is available to all.
Software Engineer at Raspberry Pi Trading. Views expressed are still personal views.
Please don't send PMs asking for support - use the forum.
I'm not interested in doing contracts for bespoke functionality - please don't ask.

carl0s
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Re: DSI Interface to Non Raspberry Pi Display

Wed May 16, 2018 5:28 pm

fruitoftheloom wrote:
Wed May 16, 2018 9:53 am
carl0s wrote:
Tue May 15, 2018 10:20 pm
I just don't get this.

Unless I'm missing something, you can use any 2-lane MIPI DSI panel you want with an stm32l4+ microcontroller, or stm32f7x9, and probably some others too.They have an lcd tft display controller which provides acceleration too (chrom-art).

What's Broadcom's problem?

I have no idea why you have resurrected an old Post, but to reiterate what has been stated it is Closed Source.

RPT have obviously signed a NDA to use the Broadcom SoC, so this question should be pointed at Broadcom:

https://www.broadcom.com/how-to-buy/#sales
It's the top result in google for Raspberry Pi DSI. I was wondering why people are still using/selling HDMI to DSI adapters for the rPi.

So by the sounds of it, you can use DSI on the Raspberry Pi. You just can't use it as an output for the binary-blob GPU driver? So you can use it but just not with any GPU acceleration? That's maybe not so bad for industrial/projects.. Not sure how that compares to the ST microcontrollers with 2-lane MIPI and dma2d / Chrom-Art acceleration (L4+ and F4/F7x9 I think).

gsh
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Re: DSI Interface to Non Raspberry Pi Display

Thu May 17, 2018 8:26 am

Again, no that's wrong, the open source drivers as developed by Eric Anholt fully support the DSI display output and support full FKMS graphics output including video and 3D.

What you don't have is the full datasheet for the hardware, but the source should have enough detail to replace this anyway...

Fill yer boots...

https://github.com/anholt/linux/blob/rp ... /vc4_dsi.c
--
Gordon Hollingworth PhD
Raspberry Pi - Director of Software Engineering

carl0s
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Re: DSI Interface to Non Raspberry Pi Display

Thu May 17, 2018 9:25 am

gsh wrote:
Thu May 17, 2018 8:26 am
Again, no that's wrong, the open source drivers as developed by Eric Anholt fully support the DSI display output and support full FKMS graphics output including video and 3D.

What you don't have is the full datasheet for the hardware, but the source should have enough detail to replace this anyway...

Fill yer boots...

https://github.com/anholt/linux/blob/rp ... /vc4_dsi.c
Ah right, well that's great then!! Thanks for clarifying ! :-)

Genoil
Posts: 1
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Re: DSI Interface to Non Raspberry Pi Display

Wed May 23, 2018 3:19 pm

Thanks for this update. We had already moved on to 96boards SBC to drive a custom panel but with the new information we might have another look at using Pi 3 / cm3.

ericbhlin
Posts: 1
Joined: Thu Apr 12, 2018 7:05 am

Re: DSI Interface to Non Raspberry Pi Display

Wed May 30, 2018 4:15 am

Hello Friends,

After studying previous articles and Mr. Anholt's blog and his amazing github sites,
I want to make my handy DSI panel works on my RPi3.

I did HW wiring and linux driver implement,
somehow, I got the DSI transaction timeouts during the initial stage like this issue ( https://github.com/anholt/linux/issues/133 )
but Mr.Anholt seems too busy to deal with that...

As you guys claimed, the DSI driver is ready,
I am wondering whether I choose the incomplete version ? (test in 4.9.y in Mr . Anholt's github)
So I would like to know which branch is confirmed to be ready and fully patched in the main stream of raspberry linux ?

Stuck here for months...

Thank you

RicardoPenders1982
Posts: 1
Joined: Tue Oct 02, 2018 12:28 am

Re: DSI Interface to Non Raspberry Pi Display

Tue Oct 02, 2018 3:33 am

I may have found the perfect display that can be salvaged from and old TomTom Go Live 1005, I just took apart my device to explore why I couldn't turn it on anymore and I found it was a dead battery...

So I was thinking that I'm not using it anymore and was only gathering dust and I just bought my first Raspi, maybe I can repurpose the 5" touch screen with my Raspi so I started to do my research and quickly found out that the display manufacturer is Samsung, another great thing I found is that all TomTom devices are running linux operating systems so even if I have to resort to writing the code from scratch the odds are pointing at the right direction so to speak and it looks like a perfect match.

In fact I watched a video on YouTube https://www.youtube.com/watch?v=vCWGMM00ZEk just now showing that you can use an Arduino MIPI DSI Shield/HDMI Adapter to drive almost any kind of display and it's compatible with Raspberry Pi 3 Model B which is the one I have, but he's clearly demonstrating that the shield works with the iPhone display and it has the same connector as the touch screen from my TomTom and he doesn't even have to do any complicated stuff with coding because the shield takes care of that.

I found someone else using FPGA with success and you can use a STM32 microcontroller chip to do the same thing and you should be able to use the same code as the official Raspi display with only the header containing the customized code for the specific display you're using...

The beautiful thing about the TomTom display is that it has the same specs as the original one and runs of the same libraries I think, it's a lot to remember and my mind is now kinda all over the place so bare with me if I'm not 100% correct, what I do know is that there's nothing you need to change from the general files used by the official Raspi screen.

I really need to figure this out and if anyone is interested in collaborating with me on this topic I can use all the help I can get because I'm planning to make a public library available on GitHub that people can use to connect almost any screen to Raspi, it will be open source and the goal is that anyone who's successful connecting any new display not listed in the database that they can upload the code and instructions so that everyone can use it for their own project.

Well, that's all I can say about it right now and I'll keep doing research on this and I'm someone who doesn't give up if I want something that isn't quite there yet and hard to find info online because I know that everything can be hacked giving it enough time, I have more than 24 years of experience in several code languages and I from what I already know and seen on YouTube I just know that I'm almost there, I can taste the success.

This can't be too difficult and if we can put our heads together with a few people we can make this happen.

By the way here's the model number of my TomTom touch screen, made by Samsung: LMS500HF10-003 - https://www.aliexpress.com/item/Origina ... 15595.html

Best regards,
Ricardo Penders CEO
[email protected]®Ez_

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