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Garbled screen during boot sequence and logout

I have a screen display issue since Ubuntu 16.04 and continuing in a fresh 18.4 LTS install. It is on one of our HTPCs running on an AMD A12 processor & 42" JVC LCD screen. The JVC is 3 years old. It is identified by the OS as 'DTV 32'.

I have placed a short video clip here to show what happens:

http://backtoburra.net.au/images/mes.../M1150001a.mp4

The Grub2 Menu loads and is displayed OK
During boot the display switches to 1080i @ 60Hz. The preferred standard for AU is 1080p @ 50Hz
The splash screen is displayed as a compressed mess at the top of the screen
The desktop (XFCE4) loads with Kodi. I have configured both to display at 1080p @ 50Hz when they load.
If I logout from the desktop (@ 47 seconds) the screen display reverts to 1080i @ 60Hz
Again, the display is garbled. logging back has to be done blindly or by a cold restart.

Is there anyway to force the display to the preferred setting 1080p @ 50Hz on boot and on a logout?

Thanks

UPDATE:
I should have mentioned it's the XFCE4 desktop and lightDM

I managed to correct the screen on logout from this article:

http://www.sudo-juice.com/lightdm-resolution/

Screen remains a mess during boot until the desktop loads

Take a look at /var/log/Xorg.0.log's EDID Modeline entries. Do you see any there that say ...1080"x50.0 or ...1080i"x50.0? I'm not in AU, but nevertheless I expect you will not. The standard you are referring to is for telecasting, not for computer screens. You should be preferring a mode during conventional PC use that conforms to your LCD's preferences, and leave it to the video player and tuner apps to use @50Hz however and whenever they deem appropriate.

Quote:

Originally Posted by FrizzledOldButt (Post 5940174)

During boot the display switches to 1080i @ 60Hz. The preferred standard for AU is 1080p @ 50Hz

i'm pretty sure you can tell the kernel to boot (i.e. grub) with a specific resolution@refreshrate.
some searches are in order...

Quote:

Originally Posted by mrmazda (Post 5940214)

Code:

[    18.067] (II) RADEON(0): Output HDMI-0 connected

[    18.067] (II) RADEON(0): Output HDMI-1 disconnected

[    18.067] (II) RADEON(0): Using exact sizes for initial modes

[    18.067] (II) RADEON(0): Output HDMI-0 using initial mode 1920x1080i +0+0

[    18.067] (II) RADEON(0): mem size init: gart size :3fdcc000 vram size: s:40000000 visible:f43d000

[    18.067] (==) RADEON(0): DPI set to (96, 96)

[    18.067] (==) RADEON(0): Using gamma correction (1.0, 1.0, 1.0)

The issue of the messed up screen is only partially resolved, as it persist during boot after the grub menu and during the splash screen. When xfce4 activates the display settings force 1920x1080 @ 50Hz.

Which brings me back to the original question; to configure/ control the display during the boot sequence or splash screen?

Quote:

Originally Posted by ondoho (Post 5940236)

i'm pretty sure you can tell the kernel to boot (i.e. grub) with a specific resolution@refreshrate.
some searches are in order...

Yes, that's for the grub menu.

Code:

GRUB_GFXMODE=1280x720

GRUB_GFXPAYLOAD_LINUX=keep

It has no effect on the display after the grub menu and before the desktop activation (XFCE4's Display Settings).

Quote:

Originally Posted by FrizzledOldButt (Post 5940479)

Yes, that's for the grub menu.

Code:

GRUB_GFXMODE=1280x720

GRUB_GFXPAYLOAD_LINUX=keep

It has no effect on the display after the grub menu and before the desktop activation (XFCE4's Display Settings).

no, there's more. options you add to the kernel boot command.
https://wiki.archlinux.org/index.php...modes_and_EDID
https://unix.stackexchange.com/quest...-vga-parameter
this is not an exhaustive list of everything you can do on the kernel command line, but it's a start. also click links within the documents i just linked.