[Mesa-dev] [PATCH v2 2/3] vulkan/wsi: Report the correct min/maxImageCount

[Neil Roberts]

Jason Ekstrand <jason at jlekstrand.net> writes:

> +   /* For true mailbox mode, we need at least 4 images:
> +    *  1) One to scan out from
> +    *  2) One to have queued for scan-out
> +    *  3) One to be currently held by the Wayland compositor
> +    *  4) One to render to
> +    */
>     caps->minImageCount = 2;
> -   caps->maxImageCount = 4;
> +   /* There is no real maximum */
> +   caps->maxImageCount = 0;

This patch as it was applied seems to leave the minImageCount as 2 on
X11. Is this possibly a mistake? Now it doesn’t match the comment above
it and there’s no explanation of this in the commit message.

It seems a little surprising that it has been changed to 4 in the
Wayland backend. Won’t this mean that every application using Vulkan,
even if it’s just a simple GUI app will end up with four large buffers
just to make the few applications that want true mailbox mode behave
correctly?

Regards,
- Neil

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