[PATCH v2 09/10] dri2: copy front to fake front in SwapBuffers

[Ville Syrjälä]

On Tue, Feb 08, 2011 at 11:42:55PM +0200, ext Pauli wrote:
> From: Pauli Nieminen <ext-pauli.nieminen at nokia.com>
> 
> DRI2SwapComplete is too late for front to fake front copy if swap is
> completed asynchronously. Client could be able to use fake front already
> before swap completes.
> 
> Moving front to fake front solves the problem but requires that driver
> is capable to copy from new front to fake front immediately after
> ScheduleSwap hook returns.
> 
> v2:
> * In blit path copy front to fake before completing the swap
> 
> Signed-off-by: Pauli Nieminen <ext-pauli.nieminen at nokia.com>
> ---
>  hw/xfree86/dri2/dri2.c |   33 +++++++++++++++++++--------------
>  1 files changed, 19 insertions(+), 14 deletions(-)
> 
> diff --git a/hw/xfree86/dri2/dri2.c b/hw/xfree86/dri2/dri2.c
> index c77ac9b..bfd72ad 100644
> --- a/hw/xfree86/dri2/dri2.c
> +++ b/hw/xfree86/dri2/dri2.c
> @@ -847,7 +847,6 @@ DRI2SwapComplete2(DRI2DrawablePtr pPriv, int frame,
>  {
>      DRI2SwapCompleteDataPtr pSwapData = swap_data;
>      ClientPtr               client = pSwapData->event.client;
> -    DrawablePtr             pDraw = pPriv->drawable;
>      CARD64                  ust = 0;
>      DRI2DrawableRefPtr      ref;
>  
> @@ -865,19 +864,6 @@ DRI2SwapComplete2(DRI2DrawablePtr pPriv, int frame,
>      if (ref == NULL)
>  	goto out;
>  
> -    if (pDraw) {
> -	BoxRec          box;
> -	RegionRec       region;
> -
> -	box.x1 = 0;
> -	box.y1 = 0;
> -	box.x2 = pDraw->width;
> -	box.y2 = pDraw->height;
> -	RegionInit(&region, &box, 0);
> -	DRI2CopyRegion(pPriv, &region, DRI2BufferFakeFrontLeft,
> -		       DRI2BufferFrontLeft);
> -    }
> -
>      if (swap_complete)
>  	swap_complete(client, pSwapData->data, type, ust, frame,
>  		pPriv->swap_count);
> @@ -911,6 +897,23 @@ DRI2WaitSwap(ClientPtr client, DRI2DrawablePtr pPriv)
>      return FALSE;
>  }
>  
> +static void
> +DRI2CopyFrontToFakeFront(DrawablePtr pDraw, DRI2DrawablePtr pPriv)
> +{
> +    if (pDraw) {
> +	BoxRec          box;
> +	RegionRec       region;
> +
> +	box.x1 = 0;
> +	box.y1 = 0;
> +	box.x2 = pDraw->width;
> +	box.y2 = pDraw->height;
> +	RegionInit(&region, &box, 0);
> +	DRI2CopyRegion(pPriv, &region, DRI2BufferFakeFrontLeft,
> +		       DRI2BufferFrontLeft);
> +    }
> +}
> +
>  int
>  DRI2SwapBuffers(ClientPtr client, DRI2DrawablePtr pPriv, CARD64 target_msc,
>  		CARD64 divisor, CARD64 remainder, CARD64 *swap_target,
> @@ -977,6 +980,7 @@ DRI2SwapBuffers(ClientPtr client, DRI2DrawablePtr pPriv, CARD64 target_msc,
>  	pPriv->refcnt++;
>  
>  	(*ds->CopyRegion)(pDraw, &region, pDestBuffer, pSrcBuffer);
> +	DRI2CopyFrontToFakeFront(pDraw, pPriv);
>  	DRI2SwapComplete2(pPriv, target_msc, 0, 0, DRI2_BLIT_COMPLETE,
>  			  func, pSwapData);
>  	return Success;
> @@ -1037,6 +1041,7 @@ DRI2SwapBuffers(ClientPtr client, DRI2DrawablePtr pPriv, CARD64 target_msc,
>  
>      DRI2InvalidateDrawable(pPriv);
>  
> +    DRI2CopyFrontToFakeFront(pDraw, pPriv);

Looks to me like the ati and intel drivers won't like this change since
they don't exchange the buffer names until the vblank event is received.
I'd say those drivers just need fixing.

>      return Success;
>  }
>  
> -- 
> 1.7.0.4
> 
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-- 
Ville Syrjälä