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

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

On 2022/03/09 17:40, Marc-André Lureau wrote:
> Hi
> 
> On Wed, Mar 9, 2022 at 12:34 PM Akihiko Odaki <akihiko.odaki@gmail.com 
> <mailto:akihiko.odaki@gmail.com>> wrote:
> 
>     On 2022/03/09 17:33, Marc-André Lureau wrote:
>      > Hi
>      >
>      > On Wed, Mar 9, 2022 at 12:21 PM Akihiko Odaki
>     <akihiko.odaki@gmail.com <mailto:akihiko.odaki@gmail.com>
>      > <mailto:akihiko.odaki@gmail.com
>     <mailto:akihiko.odaki@gmail.com>>> wrote:
>      >
>      >
>      >     If it is expected that dpy_gfx_update is required, it should call
>      >     dpy_gfx_update. I agree it is not a right timing to fix vnc
>     to remove
>      >     the implicit update as it is pre-existing.
>      >     However the lack of dpy_gfx_update call is a regression and
>     should
>      >     be fixed.
>      >
>      >
>      > Calling dpy_gfx_update is done when the scanount.kind is SURFACE.
>      >
>      > dpy_gfx_update is specific to SURFACE, GL uses dpy_gl_update.
>      >
>      > --
>      > Marc-André Lureau
> 
>     egl-headless requires non-OpenGL to display the surface content even if
>     scanout.kind is not SURFACE. Calling dpy_gfx_update is done when the
>     scanount.kind is SURFACE is not enough.
> 
> 
> We are going in circles... egl-headless call dpy_gfx_update on 
> dpy_gl_update.
> -- 
> Marc-André Lureau

Ok, let me summarize the situation.

The problem occurs in the following condition.
1. register_displaychangelistener of console_select is called for a 
non-OpenGL display.
2. scanout.kind is SURFACE_TEXTURE or SURFACE_DMABUF.
3. egl-headless is employed.

dpy_gfx_switch and dpy_gfx_update need to be called to finish the 
initialization or switching of the non-OpenGL display. However, the 
proposed patch only calls dpy_gfx_switch.

vnc actually does not need dpy_gfx_update because the vnc implementation 
of dpy_gfx_switch implicitly does the work for dpy_gfx_update, but the 
model of ui/console expects the two of dpy_gfx_switch and dpy_gfx_update 
is separated and only calling dpy_gfx_switch violates the model. 
dpy_gfx_update used to be called even in such a case before and it is a 
regression.

Regards,
Akihiko Odaki