No output on display with Weston using fbdev backend

[nsolanki at codeaurora.org]

On 2018-03-21 19:42, nsolanki at codeaurora.org wrote:
> On 2018-03-21 14:52, Pekka Paalanen wrote:
>> On Wed, 21 Mar 2018 14:40:13 +0530
>> nsolanki at codeaurora.org wrote:
>> 
>>> Hi Wayland Team,
>>> 
>>> 
>>> I am using weston 1.9.0-r0 version and compiled weston for fbdev
>>> backend.
>>> 
>>> But I do not see any output on display. Basically I do not see call
>>> reaching to "ioctl(fd, FBIOPUT_VSCREENINFO, &varinfo)" in function
>>> fbdev_set_screen_info().
>>> 
>>> 
>>> So, if I add a call "ioctl(fd,  FBIOPUT_VSCREENINFO, &varinfo)" in
>>> function fbdev_output_repaint_pixman(), I can see output on display.
>>> 
>>> Should I add FBIOPUT_VSCREENINFO ioctl in function
>>> fbdev_output_repaint_pixman() ?
>>> Can you please help me regarding this?
>> 
>> Hi,
>> 
>> it is unlikely to find help with such an old Weston, even more so with
>> the fbdev backend which at least I would like to just delete already.
>> 
>> But the fbdev backend is still in Weston, so I'd recommend trying a
>> more recent version. You can also check git to see if there are code
>> changes in the fbdev-backend.
>> 
>> I don't think FBIOPUT_VSCREENINFO at every repaint is good in any 
>> case.
>> 
>> You might be interested in reviewing this patch or the whole series:
>> https://patchwork.freedesktop.org/patch/200333/
>> 
>> What I've occasionally tested the fbdev-backend, I've never needed a
>> call to FBIOPUT_VSCREENINFO, so your use case must be somehow
>> different. Explaining exactly how and in what kind of a system and
>> environment you are running Weston could help. E.g. is it a secondary
>> fbdev device, or using UDL driver.
>> 
>> 
>> Thanks,
>> pq
> 
> Hi,
> 
> In our FB driver FBIOPUT_VSCREENINFO internally calls a commit() call,
> which actually displays content on panel.
> So, it is needed it seems. I am not sure how drawing in mmap() ed
> memory by opening /dev/fb0 can display content on panel without a
> commit() call as weston is currently doing.
> 
> 
> Thanks
> Namit


One more query is when (on what events) function fbdev_output_reenable() 
should be called?
I am not seeing session_notify() fnction call .