[PATCH 4/6] libweston: fbdev: set fb device info upon the first run.

[nerdopolis]

On Tuesday, October 3, 2017 2:44:47 AM EDT Pekka Paalanen wrote:
> On Mon, 02 Oct 2017 23:14:26 -0400
> nerdopolis <bluescreen_avenger at verizon.net> wrote:
> 
> > On Tuesday, September 26, 2017 9:45:43 AM EDT Pekka Paalanen wrote:
> > > On Thu, 14 Sep 2017 23:08:51 -0400
> > > nerdopolis <bluescreen_avenger at verizon.net> wrote:
> > >   
> > > > On Wednesday, September 6, 2017 8:17:21 AM EDT nerdopolis wrote:  
> > > > > This attempts to wake up secondary framebuffer devices
> > > > > (/dev/fb1 and up) as usually these devices start powered off, and
> > > > > the FBIOPUT_VSCREENINFO ioctl turns it on. This was tested on a
> > > > > qemu system with the options:
> > > > > 
> > > > > -vga none -device VGA,id=video0 -device secondary-vga,id=video1 \
> > > > > -device secondary-vga,id=video2
> > > > > ---
> > > > >  libweston/compositor-fbdev.c | 7 +++++++
> > > > >  1 file changed, 7 insertions(+)
> > > > > 
> > > > > diff --git a/libweston/compositor-fbdev.c b/libweston/compositor-fbdev.c
> > > > > index b4f0685c..a9cc08be 100644
> > > > > --- a/libweston/compositor-fbdev.c
> > > > > +++ b/libweston/compositor-fbdev.c
> > > > > @@ -356,6 +356,13 @@ fbdev_frame_buffer_open(struct fbdev_output *output, const char *fb_dev,
> > > > >  		return -1;
> > > > >  	}
> > > > >  
> > > > > +	/* Attempt to correct the framebuffer settings */
> > > > > +	if (fbdev_set_screen_info(output, fd,
> > > > > +	                          &output->fb_info) < 0) {
> > > > > +		weston_log("Failed to set mode settings. "
> > > > > +		           "Attempting to open output anyway.\n");
> > > > > +	}
> > > > > +
> > > > >  	/* Grab the screen info. */
> > > > >  	if (fbdev_query_screen_info(output, fd, screen_info) < 0) {
> > > > >  		weston_log("Failed to get frame buffer info: %s\n",
> > > > >     
> > > > Hi
> > > > 
> > > > Nix this one, I tried it on a UDL (USB display link device) framebuffer, and it
> > > > changes the resolution/vsync that my screen cannot handle, and I'll need to 
> > > > figure out why it does that (as UDL (the framebuffer only one) starts off) with
> > > > the screen all green...
> > > > 
> > > > ...It worked for QEMU, but not for real hardware
> > > > 
> > > > Sorry about this...
> > > > ...I'll try to see what I can come up with, and why it does that....  
> > > 
> > > Hi,
> > > 
> > > yeah, we definitely do not want to set_screen_info before first
> > > query_screen_info. If there is something valid set already, we want to
> > > keep it. If there is not, then how do you know what to set?
> > > 
> > > What screen info values do you think this patch is setting? All
> > > zeroes? ;-)
> > >   
> > Thanks for all the reviews!
> > 
> > This was an attempt to use the fact that set_screen_info sends the 
> > FBIOPUT_VSCREENINFO ioctl, which turns on the screen (if it's a /dev/fb1 as 
> > those usually are off upon boot. At least with the DisplayLink devices, and 
> > secondary-vga devices I've tested on)
> > 
> > I seem to have fixed this, It works on my QEMU configuration I mentioned,
> > it does not throw my screen out of wack on real hardware, but I think there is 
> > a bug with UDL (displaylink) or something where Plymouth starts, and freezes 
> > the display, and prevents the framebuffer from displaying (even when I cat 
> > /dev/urandom
> > into /dev/fb1 as a test...
> > 
> > This is with the udl driver (not udlfb), ...and this might be out of the
> > concern of Weston.
> 
> Hm, wouldn't Plymouth be using DRM KMS, not fbdev?
> KMS usage will "hide" the fbdev contents by design. A bug in the driver
> is possible, or then the KMS usage in both Weston and Plymouth is
> missing bits, like handling pageflips never working or not setting
> dirty rects or something. Oh yeah, Weston doesn't do multi-card either.
> 
It's a bug in the driver. I have the udl driver as the second card on seat1, so
this is not an issue with weston multi-card. This was more 'I got it to work on
a VM but not quite right on my real hardware, but because it seems to be due to
a lower level issue with the udl driver'.. I tried to turn off plymouth and ran
Weston on the UDL device, and it is just black. seems to be the fb emulation...
> 
> Thanks,
> pq