On 2025/10/15 19:45, Alex Bennée wrote:
Akihiko Odaki <[email protected]> writes:
On 2025/10/14 20:12, Alex Bennée wrote:
From: Dongwon Kim <[email protected]>
This partially reverts commit
77bf310084dad38b3a2badf01766c659056f1cf2
which causes some guest display corruption when gtk-gl-area
is used for GTK rendering (e.g. Wayland Compositor) possibly due to
simulataneous accesses on the guest frame buffer by host compositor
and the guest.
Fixes: 77bf310084 ("ui/gtk: Draw guest frame at refresh cycle")
Reported-by: Dmitry Osipenko <[email protected]>
Reported-by: Alex Bennée <[email protected]>
Tested-by: Alex Bennée <[email protected]>
Tested-by: Dmitry Osipenko <[email protected]>
Reviewed-by: Alex Bennée <[email protected]>
Reviewed-by: Dmitry Osipenko <[email protected]>
Cc: Marc-André Lureau <[email protected]>
Cc: Vivek Kasireddy <[email protected]>
Signed-off-by: Dongwon Kim <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Alex Bennée <[email protected]>
Message-ID: <[email protected]>
Cc: [email protected]
---
ui/gtk-gl-area.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/ui/gtk-gl-area.c b/ui/gtk-gl-area.c
index 05fc38096ec..9a11c9b4d18 100644
--- a/ui/gtk-gl-area.c
+++ b/ui/gtk-gl-area.c
@@ -165,7 +165,6 @@ void gd_gl_area_refresh(DisplayChangeListener *dcl)
if (vc->gfx.guest_fb.dmabuf &&
qemu_dmabuf_get_draw_submitted(vc->gfx.guest_fb.dmabuf)) {
- gd_gl_area_draw(vc);
I suggested adding code comment for the lack of gd_gl_area_draw() here
a while ago but it seems it is missed since then:
https://lore.kernel.org/qemu-devel/[email protected]/
The removal of this function call itself looks good to me.
What comment would you like - its not clear from the thread what I
should add.
Below is an idea of comment:
===
gd_egl_refresh() calls gd_egl_draw() if a DMA-BUF draw has already
been submitted, but this function does not call gd_gl_area_draw() in
such a case due to display corruption.
Calling gd_gl_area_draw() is necessary to prevent a situation where
there is a scheduled draw event but it won't happen bacause the window
is currently in inactive state (minimized or tabified). If draw is not
done for a long time, gl_block timeout and/or fence timeout (on the
guest) will happen eventually.
However, it is found that calling gd_gl_area_draw() here causes guest
display corruption on a Wayland Compositor. The display corruption is
more serious than the possible fence timeout so gd_gl_area_draw() is
omitted for now.
===
In the thread, it was discussed that the removal of gd_gl_area_draw()
can cause a regression but it is necessary to fix a bigger problem
(display corruption on Wayland), and I suggested to note the regression
so that we won't lose track of it.
To remind of the regression, the comment first describes it omits
gd_gl_area_draw(), and then explains why omitting gd_gl_area_draw() can
cause a problem, which once fixed by the reverted change. Finally, it
explains that omitting gd_gl_area_draw() is necessary to avoid display
corruption on Wayland.
Regards,
Akihiko Odaki
