Re: [PATCH v3 12/12] ui/console: call gfx_switch() even if the current scanout is GL

[Akihiko Odaki <akihiko.odaki@gmail.com>]

On 2022/03/07 20:50, Marc-André Lureau wrote:
> Hi
> 
> On Mon, Mar 7, 2022 at 2:35 PM Akihiko Odaki <akihiko.odaki@gmail.com> wrote:
>>
>> On 2022/03/07 19:19, Marc-André Lureau wrote:
>>> Hi Akihiko
>>>
>>> On Mon, Mar 7, 2022 at 12:09 PM Akihiko Odaki <akihiko.odaki@gmail.com> wrote:
>>>>
>>>> On 2022/03/07 16:46, marcandre.lureau@redhat.com wrote:
>>>>> From: Marc-André Lureau <marcandre.lureau@redhat.com>
>>>>>
>>>>> egl-headless depends on the backing surface to be set before texture are
>>>>> set and updated. Display it (update=true) iff the current scanout kind
>>>>> is SURFACE.
>>>>
>>>> egl-headless does not dynamically call register_displaychangelistener
>>>> and has console associated (console_select would not affect egl-headless
>>>> itself) so this should not be necessary.
>>>
>>> Could you help me understand, what should not be necessary?
>>
>> I read the description as it sets the backing surface for egl-headless
>> when register_displaychangelistener or console_select is called. The
>> change is not necessary.
> 
> Without it, gfx_switch is not called to set the new surface. Switching
> console with VNC would fail (via ctrl+alt+num).

Yes, but that is not because egl-headless requires its dpy_gfx_switch to 
be called. It is because vnc does not receive the surface. The patch 
adds a call of dpy_gfx_switch no matter if the receiver is an OpenGL 
display or not, but an OpenGL display would not need one.

> 
>>
>>>
>>>> The remaining problem with egl-headless is that egl-headless renders the
>>>> image to DisplaySurface, and a non-OpenGL display (namely vnc) has to
>>>> consume it instead of texture even when con->scanout.kind is
>>>> SCANOUT_TEXTURE or SCANOUT_DMABUF.
>>>
>>> This is already happening, because egl-headless calls dpy_gfx_update().
>>
>> It is not called when register_displaychangelistener or console_select
>> is called by non-OpenGL display consuming the DisplaySurface.
> 
> When displaychangelistener_display_console() is called with
> con->scanount.kind == SCANOUT_SURFACE, it calls gfx_update(update ==
> TRUE), and thus calls gfx_update on the whole surface.
> 

con->scanout.kind is SCANOUT_TEXTURE or SCANOUT_DMABUF when egl-headless 
is rendering to surface. It would not call gfx_update in the case.

Regards,
Akihiko Odaki