Latest build (r72) still does not work with 7in touch screen about chromium_os-raspberry_pi

[yunshansimon]

At last, we got an official 7inch display. The magic to fix this issue is changing dtoverlay=vc4-kms-v3d,cma-128 to dtoverlay=vc4-fkms-v3d,cma-128 in config.txt . Good luck!

[nmcain]

From my testing, you want something that does not require a Goodix or Silead touch driver.

[yunshansimon]

if you can provide /var/log/messages and shot screen of evtest, that will make things easier.

[akavkl]

In r72 HDMI driver 2 forces to HDMI hence dsi doesn't work

[yunshansimon]

Any flags in config.txt like hdmi_drive=2 are editable. You can modify them regard as your hardware. dtoverlay=vc4-kms-v3d,cma-128 is only necessary for Chromium OS.

[nmcain]

How do I modify config.txt inside of chromium os?

…

On Mon, Feb 18, 2019 at 7:19 PM Yang Tsao ***@***.***> wrote: Any flags in *config.txt* like hdmi_drive=2 are editable. You can modify them regard as your hardware. dtoverlay=vc4-kms-v3d,cma-128 is only necessary for Chromium OS. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#16 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AR0yHPm49264vdmFsrr4y0PtheMzXPy2ks5vO21QgaJpZM4aXSjs> .

[akavkl]

Write protected hence couldn't change it

[akavkl]

Only possible way now is using ssh and replacing it with modified one

[yunshansimon]

Does it work? If it does, please share your knowledge about it.

[nmcain]

How do I get the touch screen working??

[Gordon1974]

Anyone found a resolution to this yet?

[MuTong233]

Yeah,I am using a 7inch touch screen,but my screen resolution is 1024x600.It works very well and everything is OK.At first,My screen is blank too,I solved it by a 3rd party power adapter.Connect the power/touch cable to a power adapter such as smartphone charger and after logged in,put the cable back.I think it's because the HDMI detection can't work very well.

[MarcKarasek]

Any resolution to this? Would like to get this working on a7" touch screen.

Did you have a hdmi connected and then switched over to touch?

[xmapst]

Does it support output to the official 7-inch touch display of raspberrypi through the display dsi interface?

[xmapst]

Which version? What needs to be configured?

[fydeos-alpha]

@xmapst
This issue was about the compatibility of the official 7-inch display with Raspberry Pi 3B / 3B+ releases. All releases were affected.

Releases on Raspberry Pi 4B is not affected.

The solution has been provided above, by adding some extra configs to config.txt under partition 12.

A couple of methods to modify this config.txt:

• Boot target Chromium OS on a Pi, but with a different display setup so that you can see UI. Enter tty shell by hitting ctrl + alt + F2, log in with username chronos. Issue the following command to:

  • Gain sudo access and read/write permission
  • Create a mount point
  • Mount partition 12: it should be mmcblk0p12, check lsblk if it is
  • Do your modification
  • Save, un-mount, reboot

  sudo su
  mount -o remount rw /
  mkdir /tmp/p12
  mount /dev/mmcblk0p12 /tmp/p12
  
  vim /tmp/p12/config.txt    
  #do your changes by changing dtoverlay=vc4-fkms-v3d,cma-128
  
  umount /tmp/p12
  reboot
  

• Or you can directly modify chromiumos_test_image_<version_string>.img on a Linux machine by mounting its partition 12 and do your modifications:

# uncompress your image file first
xz -d  chromiumos_test_image_<version_string>.img.xz

# add its partition mappings to your host
sudo kpartx -a chromiumos_test_image_<version_string>.img

# list its partition mappings, take note of the loop device it has created
sudo kpartx -l chromiumos_test_image_<version_string>.img

# We will use loop0 as an example, create a mount point, mount it
sudo mkdir /mnt/crosp12
sudo mount -t ext2 /dev/mapper/loop0p12 -o ro /mnt/crosp12

# do your change, by changing dtoverlay=vc4-fkms-v3d,cma-128
sudo vim /mnt/crosp12/config.txt

# Once changes are made and saved, delete the mappings
sudo kpartx -d chromiumos_test_image_<version_string>.img

[gchino]

mount /dev/sda12 /tmp/p12
At this line, i received an error stating that special device /dev/sda12 does not exist
how can i rectify this?

After using

@xmapst
This issue was about the compatibility of the official 7-inch display with Raspberry Pi 3B / 3B+ releases. All releases were affected.

Releases on Raspberry Pi 4B is not affected.

The solution has been provided above, by adding some extra configs to config.txt under partition 12.

A couple of methods to modify this config.txt:

• Boot target Chromium OS on a Pi, but with a different display setup so that you can see UI. Enter tty shell by hitting ctrl + alt + F2, log in with username chronos. Issue the following command to:

  • Gain sudo access and read/write permission
  • Create a mount point
  • Mount partition 12: it should be mmcblk0p12, check lsblk if it is
  • Do your modification
  • Save, un-mount, reboot

  sudo su
  mount -o remount rw /
  mkdir /tmp/p12
  mount /dev/mmcblk0p12 /tmp/p12
  
  vim /tmp/p12/config.txt    
  #do your changes by changing dtoverlay=vc4-fkms-v3d,cma-128
  
  umount /tmp/p12
  reboot
  

• Or you can directly modify chromiumos_test_image_<version_string>.img on a Linux machine by mounting its partition 12 and do your modifications:

# uncompress your image file first
xz -d  chromiumos_test_image_<version_string>.img.xz

# add its partition mappings to your host
sudo kpartx -a chromiumos_test_image_<version_string>.img

# list its partition mappings, take note of the loop device it has created
sudo kpartx -l chromiumos_test_image_<version_string>.img

# We will use loop0 as an example, create a mount point, mount it
sudo mkdir /mnt/crosp12
sudo mount -t ext2 /dev/mapper/loop0p12 -o ro /mnt/crosp12

# do your change, by changing dtoverlay=vc4-fkms-v3d,cma-128
sudo vim /mnt/crosp12/config.txt

# Once changes are made and saved, delete the mappings
sudo kpartx -d chromiumos_test_image_<version_string>.img

the display shows up on the screen but touch controls do not work what so ever

[zan73]

The line:
sudo mount -t ext2 /dev/mapper/loop0p12 -o ro /mnt/crosp12
Should be:
sudo mount -t msdos /dev/mapper/loop0p12 -o rw /mnt/crosp12

[nico151999]

Is there a list of supported touch screens? Would prefer a screen around 10".