DPI mode with May 15th eeprom

[acidtech]

On an RPi 4, DPI LCD will not display anything after updating to May 15th bootloader. The Display is active, hsync, vsync, dotclock and data enable are all active, but the display is blank.

bootloader_version info:
May 15 2020 11:05:52
version 23a9f59b85f5a81bb2eec455e064ef9905216322 (release)
timestamp 1589537152

Using the same SD image with the stable bootloader from April DPI LCD starts up correctly.
Using the same SD image on a second RPi4 with the May 15 bootloader I get just a blank screen.
After reverting that RPi4 back to the April bootloader the problem goes away.

Note this image is running kernel: Linux retropie 4.19.97-v7l+ #1294 SMP Thu Jan 30 13:21:14 GMT 2020 armv7l GNU/Linux.

I also tried with an image using kernel 5.4. Same problem.

Note I was testing the beta bootloader so I could setup a USB SSD when I found this problem, then I back tracked to my previous image which still had the problem, and then I tried my previous image with another RPi4 with the stable eeprom bootloader.

Hoping this is something stupid on my part.

[timg236]

There are no plans to support anything except HDMI for a diagnostics screen the bootloader. There's no way to automatically probe for other displays and there isn't enough code space in the L2 cache for the drivers.
For debugging boot issues see BOOT_UART or NETCONSOLE here
https://www.raspberrypi.org/documentation/hardware/raspberrypi/bcm2711_bootloader_config.md

[acidtech]

You are misunderstanding me. The problem isn't showing the bootloader screen. The problem is when I switched to the beta bootloader using a working SD card, NORMAL DPI LCD was black ALWAYS. No screen ever came up. The only change was the bootloader version. Why the bootloader would affect this is WHY I posed this since I dont see why a bootloader should have effected this at all.

Switch back to the current stable bootloader, no other change, same SD card, and Pi4 boots and displays the console correctly.

Note, I can log in via SSH after the board boots using the beta bootloader just fine so I know the PI is booting into the SD card well past the bootloader. Just no DPI LCD display at all. There is hsync, vsync dotclock and data enable signals but no data on any RGB pins.

[JamesH65]

I cannot yet see how that can happen if the only change is the bootloader. Are you sure tha is the only change, or could there also be firmware/kernel changes?

[timg236]

Use the Raspberry Pi Imager to put the default production EEPROM on there. If the black screen persists then as @JamesH65 says it will be an issue with either the firmware or the 5.4 kernel from rpi-update.

To revert
sudo BRANCH=stable rpi-update

[acidtech]

As I said in my previous posts, the STABLE EEPROM bootloader does NOT exhibit this problem. Only the BETA EEPROM bootloader does. I THOUGHT you would want to check out this potential problem with the BETA EEPROM bootloader since I thought the point of the beta was to FIND and FIX problems before making it the stable release. As I said in my first post I am using 4.19 kernel. I also tested the problem on the 5.4 kernel and found it to also be a problem there but I am SPECIFICALLY using an existing SD image that works with the stable bootloader without a problem. Only when I load the beta bootloader to the eeprom does this problem crop up. No other changes were made to the RPI4 and NO changes were made the my SD card image AT ALL while testing to figure out this but. Nathan Scherdin

…

On Tue, May 26, 2020 at 10:21 AM Tim Gover ***@***.***> wrote: Use the Raspberry Pi Imager to put the default production EEPROM on there. If the black screen persists then as @JamesH65 <https://github.com/JamesH65> says it will be an issue with either the firmware or the 5.4 kernel from rpi-update. To revert sudo BRANCH=stable rpi-update — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#1397 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AE3QXKNKMWDCMSLT33J3YATRTP3BLANCNFSM4NJZILEQ> .

[acidtech]

James Hughes, After I found this problem I went back and eliminated all other variables to narrow down the problem. I made sure I had a working clean image(my control image SD) of Raspbian running 4.19 kernel. I used an unmodified RPi4 to test and it worked correctly(DPI LCD comes up fine). I then updated that RPI4 to the stable eeprom release using another SD image(not my control image). After updating the eeprom I booted my control SD and DPI LCD came up fine. Then I updated the RPI4 to the beta eeprom release using the other SD image. I then booted the RPI4 with my control SD again. This time no DPI display. Just blank. Has valid HSYNC, VSYNC, DOTCLOCK and DATAENABLE but not RGB DATA coming out any pins. Nathan Scherdin

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On Tue, May 26, 2020 at 10:14 AM James Hughes ***@***.***> wrote: I cannot yet see how that can happen if the only change is the bootloader. Are you sure tha is the only change, or could there also be firmware/kernel changes? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#1397 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AE3QXKLAZ7NR5XRDBSKULG3RTP2GBANCNFSM4NJZILEQ> .

[timg236]

I've passed this on, not sure if anyone has a DPI display to hand

[acidtech]

For testing, if you have a scope, you don't need a display. Just check some of the DPI RGB pins for signals. Should see something on nearly any RGB pin even if it is only "displaying" the usual "message of the day" and command prompt. When using the beta bootloader my RGB pins all remain low without changes, only hsync, vsync, dotclk and dataenable are active. Let me know if you want want me to test something. I'll be happy to help however I can. Nathan Scherdin

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On Tue, May 26, 2020 at 11:18 AM Tim Gover ***@***.***> wrote: I've passed this on, not sure if anyone has a DPI display to hand — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#1397 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AE3QXKKVCSNLWJ533BLWCPLRTQBWPANCNFSM4NJZILEQ> .

[timg236]

Don't have one of those either, I'll upload a binary with a mini patch which resets a few more HVS registers before starting. Failing that, I might be able to take a look towards the end of next week if I visit the lab.

[timg236]

Best guess without a debugger or DPI display
pieeprom-1c942e-hvs-reset.zip

[acidtech]

Thank you. I will try to test this today. Nathan Scherdin

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On Tue, May 26, 2020 at 11:53 AM Tim Gover ***@***.***> wrote: Best guess without a debugger or DPI display pieeprom-1c942e-hvs-reset.zip <https://github.com/raspberrypi/firmware/files/4684392/pieeprom-1c942e-hvs-reset.zip> — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#1397 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AE3QXKNQ4OWI7PKOLZC2OWTRTQFYZANCNFSM4NJZILEQ> .

[timg236]

DISABLE_HDMI=1 in the bootloader config is also worth trying because that prevents any HVS initialisation

[vol-2]

Having a similar issue since May 15th. "dpi24" overylay results in a blank screen on my VGA LCD attached; the pi still boots though, and can run headless over SSH. However, using a Gert666 interface results in no boot at all.

Tried DISABLE_HDMI=1 no luck. I'll give the patched pieeprom a shot today or tomorrow.

[acidtech]

This appears to have worked. Thank you. For those who dont know how here is the command to update using this file: sudo rpi-eeprom-update -d -f pieeprom-1c942e-hvs-reset.bin Note I used the -d option to restore config to defaults just in case something may have been corrupt in my config. Nathan Scherdin

…

On Tue, May 26, 2020 at 1:51 PM Tim Gover ***@***.***> wrote: DISABLE_HDMI=1 in the bootloader config is also worth trying because that prevents any HVS initialisation — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#1397 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AE3QXKONEAVN3VU7ZZK46FLRTQTWNANCNFSM4NJZILEQ> .

[vol-2]

Didn't work for my setup, but I am on linux 5.4. Could be an additional issue.
Going to revert the linux via rpi-update.