Re Weston with fbdev-backend shows blank screen on display

[Pekka Paalanen]

On Wed, 26 Jul 2017 20:16:42 +0530
saikishore <saik710 at gmail.com> wrote:

> Date: Wed, 26 Jul 2017 16:38:53 +0300
> From: Pekka Paalanen <ppaalanen at gmail.com>
> To: saikishore <saik710 at gmail.com>
> Cc: wayland-devel at lists.freedesktop.org
> Subject: Re: Weston with fbdev-backend shows blank screen on display
> Message-ID: <20170726163853.4ec8913f at eldfell>
> Content-Type: text/plain; charset="utf-8"
> 
> On Wed, 26 Jul 2017 17:24:33 +0530
> saikishore <saik710 at gmail.com> wrote:
> 
> > Hi,
> > I have ran weston with fbdev-backend  on my embedded platform with no  
> input
> > devices (evdev is not enabled) and the below is log and i see blank  
> screen.
> > Any advice on this please? it will be great help to me
> >
> >
> > #  weston-launch -- --backend=fbdev-backend.so
> >
> >
> > Date: 1970-01-01 UTC
> > [00:00:00.439] weston 1.7.0  
> 
> Hi,
> 
> any reason why so old Weston?
> 
> Nothing in the log looks wrong, Weston thinks everything works fine.
> Try running weston-simple-shm when Weston is running. If that shows up,
> then weston-desktop-shell has problems.
> 
> Weston usually does not like running without input devices, but in that
> case it should just exit gracefully.
> 
> Is fbcon working right? Can you run any old fbdev programs like 'fbi'?
> 
> 
> Thanks,
> pq
> 
> 
> Hi pekka
> Thanks for your reply. We internally use buildroot for building embedded
> Linux and in that when I enable Weston package it's coming as 1.7 version
> hence using it.

Hi,

that shouldn't prevent you from writing or finding a recipe for a newer
Weston.

I would also recommend building and running Weston on a normal Linux
desktop system, so that you get a feeling of how it should work.

Running 'weston' in a terminal window in a Wayland or X11 session will
open Weston in a window.

'weston-launch' cannot be used in a terminal window, it must always be
ran in a virtual terminal. The same goes for using the fbdev-backend.

Running via ssh or a serial terminal have their own quirks, but none
requires code modifications.

> And in weston-launch app I have commented out code lines of ioctl call for
> input devices because I am running on emulation environment hence initally
> trying to bring up Weston on FB first.

You should not need to do that at all. I do not know what you did, but
if you also broke the VT handling in there, I wouldn't be surprised of
a black screen.

Please, make an input device available, or upgrade to a version of
Weston that has a weston.ini option to allow running without input
devices. The option is "require-input=false" in [core] section of
weston.ini, explained in the weston.ini man page. It appeared in Weston
2.0.0.

> On FB we are booting with default image which is coming fine with Linux
> boot.

Where does it come fine to? A desktop? A VGA text mode virtual terminal?
fbcon?

Only fbcon (graphical mode virtual terminal) is the right environment
for Weston with the fbdev-backend.

> After Linux boot I have launched this weston-launch app then immediately
> this display goes blank screen.
> 
> By the way I didn't used any Weston.ini file and as per log it is taking
> some default. How to give Weston.ini as input this app weston-launch??.

'man weston.ini' tells you how Weston finds the file. The first file
found is taken, the rest are ignored.

> Is weston-simple-shm can also run similar to weston-launch ? By the way I
> am running from shell terminal of Linux boot. And what is the command line
> parameters of weston-simple-shm.

weston-simple-shm is a Wayland application. It requires a running
Wayland server (e.g. Weston), and has no options. You can start it via a
remote login once weston is running.


Thanks,
pq
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