Re: [PATCH] virtio-gpu: Respect graphics update interval for EDID

[Akihiko Odaki <akihiko.odaki@xxxxxxxxx>]

2021年2月22日(月) 19:57 Gerd Hoffmann <kraxel@xxxxxxxxxx>:
>
> On Sun, Feb 21, 2021 at 10:34:14PM +0900, Akihiko Odaki wrote:
> > This change introduces an additional member, refresh_rate to
> > qemu_edid_info in include/hw/display/edid.h.
> >
> > This change also isolates the graphics update interval from the
> > display update interval. The guest will update the frame buffer
> > in the graphics update interval, but displays can be updated in a
> > dynamic interval, for example to save update costs aggresively
> > (vnc) or to respond to user-generated events (sdl).
> > It stabilizes the graphics update interval and prevents the guest
> > from being confused.
>
> Hmm.  What problem you are trying to solve here?
>
> The update throttle being visible by the guest was done intentionally,
> so the guest can throttle the display updates too in case nobody is
> watching those display updated anyway.

Indeed, we are throttling the update for vnc to avoid some worthless
work. But typically a guest cannot respond to update interval changes
so often because real display devices the guest is designed for does
not change the update interval in that way. That is why we have to
tell the guest a stable update interval even if it results in wasted
frames.

Regards,
Akihiko Odaki

>
> take care,
>   Gerd
>