EXA: Handle separate alpha maps properly in Composite fallback, take two.

Preserve the EXA ABI by introducing a new driver flag EXA_SUPPORTS_PREPARE_AUX.
If the driver doesn't set this flag, we have to assume any Prepare/FinishAccess
driver hooks can't handle the EXA_PREPARE_AUX* indices, so we move out such
pixmaps at PrepareAccess time.

Fixes https://bugs.freedesktop.org/show_bug.cgi?id=18710 .

Signed-off-by: Michel Dänzer <daenzer@vmware.com>

3 files changed, 51 insertions, 1 deletions

diff --git a/exa/exa.c b/exa/exa.c
index a64769905..5425f902e 100644
--- a/exa/exa.c
+++ b/exa/exa.c
@@ -538,6 +538,12 @@ ExaDoPrepareAccess(DrawablePtr pDrawable, int index)
     if (pExaScr->info->PrepareAccess == NULL)
         return;
 
+    if (index >= EXA_PREPARE_AUX0 &&
+        !(pExaScr->info->flags & EXA_SUPPORTS_PREPARE_AUX)) {
+        exaMoveOutPixmap (pPixmap);
+        return;
+    }
+
     if (!(*pExaScr->info->PrepareAccess) (pPixmap, index)) {
         ExaPixmapPriv (pPixmap);
         if (pExaPixmap->score == EXA_PIXMAP_SCORE_PINNED)
@@ -597,6 +603,13 @@ exaFinishAccess(DrawablePtr pDrawable, int index)
     if (!exaPixmapIsOffscreen (pPixmap))
         return;
 
+    if (index >= EXA_PREPARE_AUX0 &&
+        !(pExaScr->info->flags & EXA_SUPPORTS_PREPARE_AUX)) {
+        ErrorF("EXA bug: Trying to call driver FinishAccess hook with "
+               "unsupported index EXA_PREPARE_AUX*\n");
+        return;
+    }
+
     (*pExaScr->info->FinishAccess) (pPixmap, index);
 }
 
diff --git a/exa/exa.h b/exa/exa.h
index 21a0f1abf..12959e127 100644
--- a/exa/exa.h
+++ b/exa/exa.h
@@ -672,6 +672,13 @@ typedef struct _ExaDriver {
          * from.
          */
         #define EXA_PREPARE_MASK        2
+        /**
+         * EXA_PREPARE_AUX* are additional indices for other purposes, e.g.
+         * separate alpha maps with Composite operations.
+         */
+        #define EXA_PREPARE_AUX0        3
+        #define EXA_PREPARE_AUX1        4
+        #define EXA_PREPARE_AUX2        5
         /** @} */
 
     /**
@@ -742,6 +749,13 @@ typedef struct _ExaDriver {
  */
 #define EXA_HANDLES_PIXMAPS             (1 << 3)
 
+/**
+ * EXA_SUPPORTS_PREPARE_AUX indicates to EXA that the driver can handle the
+ * EXA_PREPARE_AUX* indices in the Prepare/FinishAccess hooks. If there are no
+ * such hooks, this flag has no effect.
+ */
+#define EXA_SUPPORTS_PREPARE_AUX        (1 << 4)
+
 /** @} */
 
 /* in exa.c */
diff --git a/exa/exa_unaccel.c b/exa/exa_unaccel.c
index c821f0da8..9a0b0e5af 100644
--- a/exa/exa_unaccel.c
+++ b/exa/exa_unaccel.c
@@ -392,6 +392,15 @@ ExaCheckComposite (CARD8      op,
 
     REGION_NULL(pScreen, &region);
 
+    /* We need to prepare access to any separate alpha maps first, in case the
+     * driver doesn't support EXA_PREPARE_AUX*, in which case EXA_PREPARE_SRC
+     * may be used for moving them out.
+     */
+    if (pSrc->alphaMap && pSrc->alphaMap->pDrawable)
+        exaPrepareAccess(pSrc->alphaMap->pDrawable, EXA_PREPARE_AUX2);
+    if (pMask && pMask->alphaMap && pMask->alphaMap->pDrawable)
+        exaPrepareAccess(pMask->alphaMap->pDrawable, EXA_PREPARE_AUX1);
+
     if (!exaOpReadsDestination(op)) {
         if (!miComputeCompositeRegion (&region, pSrc, pMask, pDst,
                                        xSrc, ySrc, xMask, yMask, xDst, yDst,
@@ -404,9 +413,17 @@ ExaCheckComposite (CARD8      op,
 
         REGION_TRANSLATE(pScreen, &region, xoff, yoff);
 
+        if (pDst->alphaMap && pDst->alphaMap->pDrawable)
+            exaPrepareAccessReg(pDst->alphaMap->pDrawable, EXA_PREPARE_AUX0,
+                                &region);
+
         exaPrepareAccessReg (pDst->pDrawable, EXA_PREPARE_DEST, &region);
-    } else
+    } else {
+        if (pDst->alphaMap && pDst->alphaMap->pDrawable)
+            exaPrepareAccess(pDst->alphaMap->pDrawable, EXA_PREPARE_AUX0);
+
         exaPrepareAccess (pDst->pDrawable, EXA_PREPARE_DEST);
+    }
 
     EXA_FALLBACK(("from picts %p/%p to pict %p\n",
                  pSrc, pMask, pDst));
@@ -433,9 +450,15 @@ ExaCheckComposite (CARD8      op,
 #endif /* RENDER */
     if (pMask && pMask->pDrawable != NULL)
         exaFinishAccess (pMask->pDrawable, EXA_PREPARE_MASK);
+    if (pMask && pMask->alphaMap && pMask->alphaMap->pDrawable)
+        exaFinishAccess(pMask->alphaMap->pDrawable, EXA_PREPARE_AUX1);
     if (pSrc->pDrawable != NULL)
         exaFinishAccess (pSrc->pDrawable, EXA_PREPARE_SRC);
+    if (pSrc->alphaMap && pSrc->alphaMap->pDrawable)
+        exaFinishAccess(pSrc->alphaMap->pDrawable, EXA_PREPARE_AUX2);
     exaFinishAccess (pDst->pDrawable, EXA_PREPARE_DEST);
+    if (pDst->alphaMap && pDst->alphaMap->pDrawable)
+        exaFinishAccess(pDst->alphaMap->pDrawable, EXA_PREPARE_AUX0);
 
     REGION_UNINIT(pScreen, &region);
 }