[HELP] HDMI 2.0 to MIPI-DSI / LVDS [SOLVED]

[Oneminde]

It might be true what you say about the production of the display, if so, then it will be very difficult to move forth.

[zyann2]

Would the snapdragon 820 dev board run the display without drivers?, and how would one match up the cable from the dev board to the screen, as it looks different?

[alex1971]

Hi!
Need help! Is very necessary datasheet LS055D1SX04!
To help you to- https://github.com/dtsinc/DTS-Sound-Integration_CAF-Android-kernel/blob/master/arch/arm/boot/dts/qcom/dsi-panel-nt35950-4k-dualmipi0-cmd.dtsi

[smoki99]

Hi there,

this is a very interesting project. But where you get the Sharp LS055D1SX04.

I was on panelook and get information, there are non available. Is this true?

Kind Regards,

Christian Mueller

[daveshah]

I've been researching the Z5 premium LCD a bit, and thought I should share what I've found. I'm currently working on an FMC breakout board for it and hopefully in the next few months I'll have a FPGA driver for it working.

The display isn't exactly the LS055D1SX04, although the driver is the same the pinout and a few other specs are different. Actually the Z5 premium LCD could be one of 6 different parts from 3 different vendors (AUO, JDI and Sharp) based on the device tree files for it. I've seen both AUO and Sharp panels "in the wild" and obtained a datasheet for one AUO part - the H546UAN01.0 - which I've uploaded here due to the attachement limit. I've definitely seen this part number on at least one eBay listing for replacement Z5 premium LCDs. As supply voltages and register configs differ slightly different LCD models/manufacturers are identified by a different resistor to ground connected to the LCD_ID pin.

The display driver (Novatek NT35950, no datasheet is available) is actually very sophisticated. In 4k mode, it supports (and quite possibly requires) compressed video to reduce the data rate to 1/3 of uncompressed 4k. The compression algorithms supported are simple streaming ones; either Qualcomm's entirely proprietary FBC or VESA's Display Stream Compression which is "open" if you pay $350. The display driver can also upscale from 1080p, compression is not needed in this mode.

Also presumably due to being at the very limit of possible pixel density, the screen doesn't have a full 3 subpixels per pixel. Instead each pixel has only two colour subpixels, and there's some magic ("subpixel rendering") on the display driver to drop subpixels with minimal loss in quality. I suppose in effect it's more like a 1440x3840 display than a full 4k one though.

The Z5 Premium uses the display in MIPI DSI Command Mode, which means that pixels are written over DSI into a framebuffer built into the display driver; saving power as it means that data does not need to be written every frame if it hasn't changed. The display driver also supports video mode without a framebuffer, by setting register B4 in page 0 from 0x01 to 0x10 (as in this DTS entry). I believe one of the reasons for using compression, as well as reducing DSI data rate, is that compressed images are stored in this framebuffer so only 1/3 the RAM is needed.

Unfortunately the connector used by the display is a pain to source (DDK BB35-PC60-3A-D8 on the display, so BB35-RC60-3A needs to be used on the board). I eventually managed to order 10 samples from a 1688 seller (the link I used no longer works but I think this is the same seller). A few places on Taobao listed it but none would sell small quantities. As far as I can tell getting a reel of 6000 would be fairly easy if ever going to MP.

[deepfire]

I've been researching the Z5 premium LCD a bit, and thought I should share what I've found. I'm currently working on an FMC breakout board for it and hopefully in the next few months I'll have a FPGA driver for it working.

daveshah, what do you think about using mentioned board like this or this. Is this even possible to use as a solution driver? What do you think is the most realistic approach to the problem?

It seems like you're developing a board yourself, would be interesting to know a little bit more details 

Also, heres some links to add for discussion:
M35 UHD LCD control board
SVX-3840 LCD Controller

Are these any good?

Also, for smoki99, to find where to buy the screen you should search "z5 premium replacement screen"
Some stores here here and here
Btw, the screens considerably dropped in price, i remember them being around $120, now only $65-70.
Maybe thats an indicator they soon get extinct, need to hurry and buy a couple myself.

[daveshah]

The Qualcomm Snapdragon 820 boards should work, you may need to develop a kernel device tree entry based on the Sharp 4k DTSI files and the Z5 Premium kernel's DTSI files. As far as is documented, the 810 used in the Z5 Premium and that the drivers are developed for uses Qualcomm FBC to compress the data; whereas the 820 only supports VESA DSC which the display should also support.

You would probably need to build a custom interface board between the dev board and display; also providing the LCD power rails (IIRC +/- 5.6V; 1.8V and 1.35V) and a backlight driver

My own plan requires driving the display from an FPGA I'm building a board to connect it to FPGA dev board with an FMC connector.

Waiting for boards to arrive at the moment, not willing the release designs yet but will soon, after a previous but similar board put 12V onto 3.3V and destroyed a ~$1200 FPGA board and I don't want that happening to anyone else.

As far as availability goes based on experience with other devices displays will be available for a long time but price may fluctuate. As well there's Sharp's LS055D1SX04 - different pinout but otherwise similar - which a distributor told me was going into mass production in November.

Rumour has it Samsung might release a phone with a 4k AMOLED around March and that will almost certainly reach its way to the spares market in a few months - based on past Samsung OLEDs maybe around the $150-200 mark. It will almost certainly use dual lane DSI and VESA DSC so FPGA code written could be reused and it could be driven from the same Qualcomm dev boards; but pinout, voltages (because it's AMOLED) and setup commands will be different.

[daveshah]

If you want the Sharp panel, which has an easier to obtain connector and I believe this DTSI file for use with a Snapdragon 820; you could try contacting one of these suppliers

http://www.panelook.com/LS055D1SX04_SHARP_5.5_LCM_inventory_27124.html

Also in large quantities it might be easier to obtain as you could probably go straight to Sharp.

Datasheet for the Sharp panel is uploaded here.

[cmhansen]

Here is an IC that is almost the same model of ic a board was using (TC358870XBG) that was linked, but this is eDP and supposed to handle 4K@60hz:
https://toshiba.semicon-storage.com/info/docget.jsp?did=15627&prodName=TC358860XBG

The eDP should work fine with the many options of standard mass-produced V-by-one with eDP display controllers.

TC358860XBG provides a compression engine which compress video data with 2-to-1 ratio. This enables
TC358860XBG to receive 4K @60fps video streams at eDP Rx, compress and send out to a dual DSI link 4K
panel for display. "A de-compress engine is expected in the DSI panel."

Now, does that sharp panel (or other two variants) have decompress built in?  It seems like the only snag was the compression... still it's essentially half the data as a raw stream so it seems like quality will not be as great... 4:2:2 requires 66% the bandwidth as 4:4:4, so it sounds it wouldn't even be as good as that really... in fact maybe only equal to 1440p@60hz.  But like mentioned, SLA printer application would still be possible if you can remove the color filter, and 30hz might be ok as a projector, and eDP is a much cleaner way than a dev board.  Still a display connector other than mipi would be best, as I understand the IGZO displays can handle the fast refresh.

[daveshah]

Now, does that sharp panel (or other two variants) have decompress built in?  It seems like the only snag was the compression... still it's essentially half the data as a raw stream so it seems like quality will not be as great... 4:2:2 requires 66% the bandwidth as 4:4:4, so it sounds it wouldn't even be as good as that really... in fact maybe only equal to 1440p@60hz.  But like mentioned, SLA printer application would still be perfectly fine, and 30hz might be ok as a projector, and eDP is a much cleaner way than a dev board.  Still a display connector other than mipi would be best, as I understand the IGZO displays can handle the fast refresh.

Although the Sharp panel does support decompression of 3:1 VESA DSC and Qualcomm FBC; I don't think it supports the proprietary and undocumented 2:1 compression in the Toshiba IC. The only display which I know supports Toshiba style compression is the LS029B3SX02; a 2.9" 1440x1440 display designed for VR applications. The Toshiba IC can I believe drive two of these at 120Hz with compression.

As far as quality goes; the compression is going to be a lot better than 4:2:2 and is genuinely 'visually lossless' (remember this is a very 'light' compression - only 2:1 or 3:1 - compared to H264 etc which can be >20:1 in many cases) on typical images, video and computer graphics. On the other hand I'm not sure how it would affect other uses  such as in an SLA printer.

I still am not sure whether or not the Sharp display will support uncompressed 4k at 30-40fps - which the Toshiba chip should support - but I'll hopefully get the hardware next week and be able to start playing around. I'll report back here or in a new thread with my findings and VHDL if I'm successful.

[cmhansen]

Pure bandwidth-wise, I still don't see how 50% video rate is less lossy than 66% (4:2:2) rate??  Hmm nvm, 422 is more like dropping data than compressing it looks.... but obviously compression adds some latency, though 2:1 may be very fast.

Also I wonder if those 3 manufactures all use the same Sharp LCD or just license?  How much effort would it take to negotiate a small mod to create a easier to use and better (lower cost too??) LCD with eDP and no decompression?  Also if they were as useful in projectors as we imagine why aren't there low-cost ones mass produced... they don't want to cannibalize their projector sales?  It's less than 2x2 as big as a 3" LCD.

To be honest I'm seeing 4k 65"+ panels very inexpensive now from alibaba, and that's nearing the size of a projector screen albeit not easy to move.  Even, walmart has a complete 49" 4k set for $250 shipped and that's about the regular price for that set.

[cmhansen]

>Chinavasion sells a 3800lumen projector that has a 5.8 LCD panel in it that can be swapped out https://www.chinavasion.com/china/wholesale/LED_Projectors/HD_Projectors/3800-Lumens-HD-LED-Projector-White/

You bring up a good point... there are already very low cost projectors using 'big' lcd's.... I imagine the thought has more than crossed their mind of using a 'practically free' in projector comparison 4k phone displays... and they have good resources I'm sure so why no 4k products yet I wonder?!  Also I wonder if a 4k TV asic supports keystoning... that's practically all that's missing from a volume 4k TV board to make a projector. (just use lens shift, it's better anyways)

[cmhansen]

I still am not sure whether or not the Sharp display will support uncompressed 4k at 30-40fps

Forget mipi - that IGZO TFT should more than support 60hz, better than a normal TFT.  If not it's mipi bus and whatever ic does decompression, would be great to get rid of that and in fact V-by-one may be better (less cruft) than eDP.  DP multi monitor over one cable is such a niche use for a ubiquitous protocol - why not use simple multiplexers / deplexers for this edge case.... besides, lower resolutions can be sent wireless too.

And... why don't TVs (even monitors) just have an external vby1 and connect an external box similar (modified) to those ~$20 android arm SOC boxes?  Then again monitors should be able to connect directly with something like vby1 to a PC, the GPU can do everything done by a TV ic and better enabling lower latency too.  HDCP to blame?

[daveshah]

Pure bandwidth-wise, I still don't see how 50% video rate is less lossy than 66% (4:2:2) rate??  Hmm nvm, 422 is more like dropping data than compressing it looks.... but obviously compression adds some latency, though 2:1 may be very fast.

Effectively the compression algorithm is optimised for typical video/image/computer graphics; resulting in a typically higher quality. It's a really simple intra-frame with a line buffer only that works in chunks of ~32 lines - not whole frames - so the latency is negligible, a lot less than a frame.

I still am not sure whether or not the Sharp display will support uncompressed 4k at 30-40fps

Forget mipi - that IGZO TFT should more than support 60hz, better than a normal TFT.  If not it's mipi bus and whatever ic does decompression, would be great to get rid of that and in fact V-by-one may be better (less cruft) than eDP.  DP multi monitor over one cable is such a niche use for a ubiquitous protocol - why not use simple multiplexers / deplexers for this edge case.... besides, lower resolutions can be sent wireless too.

I believe that IGZO means the transistors can switch faster, but it doesn't affect the response time of the crystals which will be a limiting factor. No idea about getting Sharp to change the driver IC, ones supporting V-by-one/eDP are generally designed for larger panels but might work. A lot of reengineering would be needed, I suspect you'd be talking minimum qtys of 100k-1M.

[daveshah]

Is 10.1" too big for a DIY projector? This panel claims to have eDP; and available stocks.

http://www.panelook.com/TV101QUM-N00_BOE_10.1_LCM_overview_26559.html

[cmhansen]

Is 10.1" too big for a DIY projector? This panel claims to have eDP; and available stocks.

http://www.panelook.com/TV101QUM-N00_BOE_10.1_LCM_overview_26559.html

Put it on an overhead and call it a day   Ultimately it's too big, and a phone screen would have a larger volume sales I'd imagine, one figure just for the xperia (recent, may not be z5 premium) was like 4 million in the first month or so.  Sharp has no contact info but AUO (Taiwan) does, only Taiwan numbers... english option but I still didn't get anywhere... I can't imagine engineering would be complex but it would be a new product.  It would have very high demand, and would be nice to be plugnplay (no disassembly or converters), I'd imagine no backlight/digitizer/glass should be less expensive and slightly more transmissive too.

For larger lower dpi SLA 10" would be better of course, and LCD can't use UV for sla anyway but that may not matter much:
https://3dprint.com/117623/uniz-slash-sla-3d-printer/
800+ DPI would be desired for smaller builds, no speed penalty.

FPGA's are kinda obsolete now anyways right?  Expensive even for diy... any chance to use CPLDs for a 'bus adapter' so to say?  A chance these could be made cheap and handle different bus types/protocols too.

This obviously needs to scale beyond 'hobby', i.e. fabs produce what an individual can't.  I've seen some good reviews on those 5.8" LCD projectors, chinavasion's model looks to be ADK btw from a search on alibaba, where there are MANY.  I doubt any of those have lens shift of any kind (fixed or variable), basic keystone probably and even I bet there's 'software' corner keystone for projector stacking, if not that should be trivial.  Also one might find a lens shift adapter to put in front instead of keystone.

[cmhansen]

Also presumably due to being at the very limit of possible pixel density, the screen doesn't have a full 3 subpixels per pixel. Instead each pixel has only two colour subpixels, and there's some magic ("subpixel rendering") on the display driver to drop subpixels with minimal loss in quality. I suppose in effect it's more like a 1440x3840 display than a full 4k one though.

You bring up a really good point, this may be what they mean by "rainbow RGB".  This is kind of like RGBW 4k UHD's as only having 3/4 as many pixels as a full UHD, or the full having 4/3 times as many, however you look at it.  If any amount of compression could make up for lost pixels, they might as well advertise 720p as 4k, that's 9x fewer pixels but hey HEVC can fit that bandwidth with 4k just perfect no?!. </rant>  "These aren't the droids you are looking for"! 

edit: RGBW sub pixel count is less it looks, think it is pentile and the z5 premium might be rgbg pentile or equivalent too:
https://en.wikipedia.org/wiki/PenTile_matrix_family

An early controversy regarding the definition or measurement of resolution of color subpixelated flat panel displays in general, and for subpixel rendered displays in particular, led many people[23][24][25] to question the resolution claims of PenTile display products.[26] One school holds that resolution is defined by the number of red, green, and blue subpixels, in groups of three, in an array in each axis.[citation needed] The other school holds that resolution is found by counting the number of line pairs, black & white (or bright and dark) lines and spaces that may be simultaneously rendered on the screen, in each axis.[5]

Also I'm not sure if it's really a ppi issue... for instance this projector:
http://www.projectorcentral.com/Sanyo-PLC-WL2500A.htm
has 3x .6" 1280x800 lcd's, that's 2515.73/3 =~ 838 ppi, that's pretty old too, igzo is supposed to enable 4x dpi than standard I believe.  '3lcd' panels are made a little different anyways, not sure how they get the density without igzo.

[cmhansen]

FYI I reached out to Chimei Innolux sales about manufacturing a desired LCD and it's been forwarded twice since yesterday... so even if they say they aren't able to, I say it's a small success.

[daveshah]

FYI I reached out to Chimei Innolux sales about manufacturing a desired LCD and it's been forwarded twice since yesterday... so even if they say they aren't able to, I say it's a small success.

Very interesting - let me know what happens! Have you also considered contacting AUO, JDI or Sharp?

[cmhansen]

I tried AUO and should try again, I haven't received reply back from the contact form and even though the rep I talked to had better english than my chinese I didn't get anywhere.  I figure Sharp doesn't want to obsolete their projector tech and no doubt they know the ramifications of a ~$20 or $30 LCD part (no contact on their website - they don't want to be bothered basically).  JDI (Sony, Toshiba, and Hitachi) are probably like Sharp (and Sharp supplies sony's z5 panel anyways).  I read samsung and sharp have licensed igzo but Innolux may also, there may be others too.  Basically any forward-looking LCD manufacturer who isn't monopolized by another company should be a good avenue.

[cmhansen]

Here's a good question - would a 7" 3840x2160 uhd 4k LCD be better for projection and SLA printing than 6" or less?  There are quite a few production projectors using 7" too, e.g.:
https://www.bhphotovideo.com/c/product/893253-REG/Pyle_Pro_prjle55_High_Def_LED_Widescreen_Projector.html

It is a good bit bigger than the 5.8" based projectors, and focal ranges may be more limited too (?).  For SLA there would be a tradeoff between size and resolution... obviously even that 10.1" 4k LCD could be focused to a smaller area for higher ppi / dpi but that will cause distortion (a collimator at the desired size may help but divergence always increases as beam diameter is shrunk).

https://www.bhphotovideo.com/c/buy/On-Camera-LCD-Monitors/ci/1984/N/4028759510?origSearch=video%20monitors
You can easily see that 7" appears to be the most common size for professional camera monitors / viewfinders so such size would immediately find use in this application as well as the most common small tablet size 7".  Isn't it ironic that a phone is the least useful application for this resolution yet it was the first available to consumers?  The highest immediate volume likely though  (If you can get around UHD 4k having exactly 150% as many subpixels as the Z5 premium screen - assuming Rainbow RGB is basically pentile).

Also compression does seem to make sense at such high resolutions and seems it will be baked into DP... it could be that putting decompression on the LCD matrix bus makes sense.

[cmhansen]

A technical reason why larger LCDs might be better to some extent is that the TFT transistor gate will likely be a smaller proportion of the subpixel, the gate lowers transmittance.
http://c8.alamy.com/comp/BB4CAC/an-active-matrix-thin-film-transistor-tft-liquid-crystal-display-a-BB4CAC.jpg

[cmhansen]

Also a very important but less thought of difference probably between 3lcd and single lcd is lumen efficiency.  A single LCD will need roughly 3x the lumen output at the lamp as a 3 lcd since each color is blocked by 2/3 the area of the LCD.  It might actually be a lot more comparable though with BEF, reflective polarizer, etc.

If you could simply remove the color filter from a panel, to get square pixels from a subpixel rectangle, you have to shrink 3x in the axis the subpixel is longest.  Resolution is limited by the longest pixel length more or less, infx1 yields a gradient, not an image.  Though... if subpixels are not side to side but vertical, you could do a horizontal shrink and get square cells in a (16/3):9 which is really close to a simple rotation, just slightly more square.  2560x1440p in such case gives 2560p x 1440(x3) = 4320x2560p after digital rotation and optical shrinking.  It would work, but it's more cumbersome than the 'right' panels.  Then there's the issue of convergence through a somewhat large dichroic prism RGB combiner x-cube or set of mirrors.

[TelenOA]

Hi, guys.

Seeing as the Xperia Z5 Premium's display has been discussed here as a possible viable 4k 60fps display (being around $55 and easily obtainable), and I've been looking into it for a DIY VR project, I figured I'd post this here:

The primary difficulty I've read regarding using this as a display is an initialization sequence being needed, and a datasheet being needed for that. However the kernal for Xperia is on GitHub, so I searched and found this. msm8994 is the Snapdragon 810 - used in the Z5 Premium. It's also for the Z5 and a ton of other devices, but only the Z5 Premium is 4k.

#include "dsi-panel-jdi-4k-dualmipi-video.dtsi" is the only 4k-related entry in that file, Googled it: found this. The "qcom,mdss-dsi-on-command" variable looks like it could, therefor, be the initialization code needed for the Z5 Premium's specific screen, and if I'm making a ton of assumptions and it turns out not to be, it should still be findable in the Xperia source on GitHub.

I have never dealt with things like initialization sequences, kernals, etc, so I think I am making a bunch of assumptions. For example JDI being noted in the entry, and JDI's never given news of a 5.5" 4k display - Sharp has, but there's no 4k entry for them. Weird. Could just be something never updated in the variable name.

These links could be useful to others, though, so there they are. Hope it helps. 

[cmhansen]

The UP board seems like a good (better?) SBC and it might be compatible with some mipi DSI displays:
https://up-community.org/forum/general-discussion/823-driving-cell-phone-lcd-with-up-board
A universal mipi dsi - dp adapter would be the best hold-over though for this and every other phone display, no intermediate SOC or scaling asic (e.g. TV board) needed really, just connect a PC or SBC of choice directly. 
 
UP 1 SOC gpu is not even half the raw gflops on paper of the adreno 430 in the SD810.  Though one GFXbench test equates it to an nVidia Tegra K1 (or possibly the Adreno 530 in one S7 version, if not the Mali):
https://youtu.be/dPJiShBIPw8?t=9m16s
And at around $100 it's also at least 5x less than an 810 dev board too.
Is the included Altera Max 10 FPGA on the newer UP^2 any good/useful?  It's only 2k LEs.

If not already linked, here's a good place to compare SBC's (many have mipi DSI):
https://www.board-db.org/