[PATCH] dri2: Update the fake front on SwapBuffers (bug 27305).

[Kristian Høgsberg]

2010/3/30 Francisco Jerez <currojerez at riseup.net>:
> It wasn't a problem before the invalidate changes (fa5103a02
> specifically) because the SwapBuffers request was unconditionally
> followed by a GetBuffers request (and GetBuffers updated the fake
> front). On DRI2.3 the client is only required to re-sync buffers when
> it gets an explicit invalidate event, so we cannot rely on this
> behavior anymore.
>
> It was reported to make the following piglit/glean test cases regress:
> texgen, coloredTexPerf2, coloredLitPerf2.

We need a link to

https://bugs.freedesktop.org/show_bug.cgi?id=27305

in the commit message, and I'd prefer to see the get_drawable_region()
cleanup in a separate patch.  Otherwise the fix looks good - the extra
DRI2CopyRegion in DRI2SwapComplete only kicks in when we have a fake
front buffer, so it wont impact regular double buffered rendering.

As for the cleanup part, I'd rather see a DRI2CopyDrawable() function
that creates the drawable region and just calls DRI2CopyRegion.
Should be ok to use that in DRI2SwapBuffers() as well, even if we end
up looking up the buffers twice.

Kristian

> Signed-off-by: Francisco Jerez <currojerez at riseup.net>
> ---
>  hw/xfree86/dri2/dri2.c |   32 ++++++++++++++++++--------------
>  1 files changed, 18 insertions(+), 14 deletions(-)
>
> diff --git a/hw/xfree86/dri2/dri2.c b/hw/xfree86/dri2/dri2.c
> index 41006da..f05bb5e 100644
> --- a/hw/xfree86/dri2/dri2.c
> +++ b/hw/xfree86/dri2/dri2.c
> @@ -217,6 +217,14 @@ find_attachment(DRI2DrawablePtr pPriv, unsigned attachment)
>     return -1;
>  }
>
> +static void
> +get_drawable_region(DrawablePtr draw, RegionPtr region)
> +{
> +    BoxRec box = { 0, 0, draw->width, draw->height };
> +
> +    REGION_INIT(draw->pScreen, region, &box, 0);
> +}
> +
>  static Bool
>  allocate_or_reuse_buffer(DrawablePtr pDraw, DRI2ScreenPtr ds,
>                         DRI2DrawablePtr pPriv,
> @@ -344,15 +352,9 @@ do_get_buffers(DrawablePtr pDraw, int *width, int *height,
>      * applications that call glXWaitX before calling glDrawBuffer.
>      */
>     if (have_fake_front && buffers_changed) {
> -       BoxRec box;
>        RegionRec region;
>
> -       box.x1 = 0;
> -       box.y1 = 0;
> -       box.x2 = pPriv->width;
> -       box.y2 = pPriv->height;
> -       REGION_INIT(pDraw->pScreen, &region, &box, 0);
> -
> +       get_drawable_region(pDraw, &region);
>        DRI2CopyRegion(pDraw, &region, DRI2BufferFakeFrontLeft,
>                       DRI2BufferFrontLeft);
>     }
> @@ -605,6 +607,7 @@ DRI2SwapComplete(ClientPtr client, DrawablePtr pDraw, int frame,
>     ScreenPtr      pScreen = pDraw->pScreen;
>     DRI2DrawablePtr pPriv;
>     CARD64          ust = 0;
> +    RegionRec       region;
>
>     pPriv = DRI2GetDrawable(pDraw);
>     if (pPriv == NULL) {
> @@ -620,6 +623,12 @@ DRI2SwapComplete(ClientPtr client, DrawablePtr pDraw, int frame,
>        return;
>     }
>
> +    /* If we're using a fake front, update it with the front buffer
> +     * contents.  */
> +    get_drawable_region(pDraw, &region);
> +    DRI2CopyRegion(pDraw, &region, DRI2BufferFakeFrontLeft,
> +                  DRI2BufferFrontLeft);
> +
>     ust = ((CARD64)tv_sec * 1000000) + tv_usec;
>     if (swap_complete)
>        swap_complete(client, swap_data, type, ust, frame, pPriv->swap_count);
> @@ -682,18 +691,13 @@ DRI2SwapBuffers(ClientPtr client, DrawablePtr pDraw, CARD64 target_msc,
>
>     /* Old DDX, just blit */
>     if (!ds->ScheduleSwap) {
> -       BoxRec box;
>        RegionRec region;
>
> -       box.x1 = 0;
> -       box.y1 = 0;
> -       box.x2 = pDraw->width;
> -       box.y2 = pDraw->height;
> -       REGION_INIT(pScreen, &region, &box, 0);
> -
>        pPriv->swapsPending++;
>
> +       get_drawable_region(pDraw, &region);
>        (*ds->CopyRegion)(pDraw, &region, pDestBuffer, pSrcBuffer);
> +
>        DRI2SwapComplete(client, pDraw, target_msc, 0, 0, DRI2_BLIT_COMPLETE,
>                         func, data);
>        return Success;
> --
> 1.6.4.4
>
>