[PATCH xserver 1/4] xwayland: Don't create a "fake" crtc for Present

[Roman Gilg]

Thanks for looking into this. You are right that the fake CRTCs are
not needed. The reason I introduced them in the past was that with a
change (reset) of the msc counter the client might want to see a
different CRTC as well. But with the persistent window structs the
CRTC stays the same all the time and the msc counter is monotonically
counting for a window so there should be no need to have different
CRTCs for different msc counters.

Tested the patch in a Plasma session with VLC and Skype.

Tested-by: Roman Gilg <subdiff at gmail.com>
Reviewed-by: Roman Gilg <subdiff at gmail.com>

On Mon, May 7, 2018 at 11:21 PM, Adam Jackson <ajax at redhat.com> wrote:
> We probably don't want a fake crtc to be visible to clients, and we
> definitely don't want to generate events every time we create such a
> fake (which would happen as a side effect from RRCrtcCreate hitting
> RRTellChanged). As it happens we're not actually using that crtc for
> anything because xwayland doesn't store any state on the crtc object,
> so it suffices to use the real crtc for the screen.
>
> Signed-off-by: Adam Jackson <ajax at redhat.com>
> ---
>  hw/xwayland/xwayland-present.c | 21 ++++-----------------
>  hw/xwayland/xwayland.h         |  1 -
>  2 files changed, 4 insertions(+), 18 deletions(-)
>
> diff --git a/hw/xwayland/xwayland-present.c b/hw/xwayland/xwayland-present.c
> index ae9f47ebae..b5ae80dcf0 100644
> --- a/hw/xwayland/xwayland-present.c
> +++ b/hw/xwayland/xwayland-present.c
> @@ -51,14 +51,10 @@ xwl_present_window_get_priv(WindowPtr window)
>      struct xwl_present_window *xwl_present_window = xwl_present_window_priv(window);
>
>      if (xwl_present_window == NULL) {
> -        ScreenPtr screen = window->drawable.pScreen;
> -
>          xwl_present_window = calloc (1, sizeof (struct xwl_present_window));
>          if (!xwl_present_window)
>              return NULL;
>
> -        xwl_present_window->crtc_fake = RRCrtcCreate(screen,
> -                                                     xwl_present_window);
>          xwl_present_window->window = window;
>          xwl_present_window->msc = 1;
>          xwl_present_window->ust = GetTimeInMicros();
> @@ -131,8 +127,6 @@ xwl_present_cleanup(WindowPtr window)
>      if (xwl_window && xwl_window->present_window == window)
>          xwl_window->present_window = NULL;
>
> -    RRCrtcDestroy(xwl_present_window->crtc_fake);
> -
>      if (xwl_present_window->frame_callback) {
>          wl_callback_destroy(xwl_present_window->frame_callback);
>          xwl_present_window->frame_callback = NULL;
> @@ -306,10 +300,13 @@ static RRCrtcPtr
>  xwl_present_get_crtc(WindowPtr present_window)
>  {
>      struct xwl_present_window *xwl_present_window = xwl_present_window_get_priv(present_window);
> +    rrScrPrivPtr rr_private;
> +
>      if (xwl_present_window == NULL)
>          return NULL;
>
> -    return xwl_present_window->crtc_fake;
> +    rr_private = rrGetScrPriv(present_window->drawable.pScreen);
> +    return rr_private->crtcs[0];
>  }
>
>  static int
> @@ -342,9 +339,6 @@ xwl_present_queue_vblank(WindowPtr present_window,
>      if (!xwl_window)
>          return BadMatch;
>
> -    if (xwl_present_window->crtc_fake != crtc)
> -        return BadRequest;
> -
>      if (xwl_window->present_window &&
>              xwl_window->present_window != present_window)
>          return BadMatch;
> @@ -454,13 +448,6 @@ xwl_present_flip(WindowPtr present_window,
>      if (!xwl_window)
>          return FALSE;
>
> -    /*
> -     * Make sure the client doesn't try to flip to another crtc
> -     * than the one created for 'xwl_window'.
> -     */
> -    if (xwl_present_window->crtc_fake != crtc)
> -        return FALSE;
> -
>      present_box = RegionExtents(&present_window->winSize);
>      damage_box = RegionExtents(damage);
>
> diff --git a/hw/xwayland/xwayland.h b/hw/xwayland/xwayland.h
> index ce290d4909..25112e2cb8 100644
> --- a/hw/xwayland/xwayland.h
> +++ b/hw/xwayland/xwayland.h
> @@ -182,7 +182,6 @@ struct xwl_present_window {
>      WindowPtr window;
>      struct xorg_list link;
>
> -    RRCrtcPtr crtc_fake;
>      uint64_t msc;
>      uint64_t ust;
>
> --
> 2.17.0
>
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