Re: (MGA) DRI locking

[Tilman Sauerbeck]

Tilman Sauerbeck [2006-07-28 14:42]:
> Michel Dänzer [2006-07-28 13:40]:
> > Are you familiar with the X server's function wrapping mechanism?
> > DRI(Do)BlockHandler() is the DRI module's wrapper of the X server's
> > BlockHandler screen hook, which it calls whenever it has run out of
> > requests and goes to sleep for a bit. For symmetry, there's a DRILock()
> > call in DRIDoWakeupHandler(), which is a wrapper for the hook the X
> > server calls before it starts processing new requests. The idea is for
> > the DRI module to automatically hold the lock whenever the X server
> > might need hardware access.
> 
> I should have asked a more specific question. While DRIBlockHandler()
> was called all the time, DRIDoBlockHandler() was only called once, which
> led to the bad DRIUnlock() call. I wanted to know when
> DRI_Do_BlockHandler() is called :)
> 
> Looking at the code again, it seems DRIDoWakeupHandler() and
> DRIDoBlockHandler() are the base functions for the job, which may be
> overridden by the DDX driver. MGA overrides both in MGADRIScreenInit().

So it seems like mga_dri.c's MGAWakeupHandler should always call
DRILock(). The attached patch implements this change - it makes glxinfo
work again. It's probably horribly wrong though... :)

glxgears still hangs in glxMakeCurrent(). Any idea what to try next?

Regards,
Tilman

-- 
A: Because it messes up the order in which people normally read text.
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diff --git a/src/mga_dri.c b/src/mga_dri.c
index a43ebe4..246e87e 100644
--- a/src/mga_dri.c
+++ b/src/mga_dri.c
@@ -363,7 +363,6 @@ void MGAGetQuiescence( ScrnInfoPtr pScrn
 {
    MGAPtr pMga = MGAPTR(pScrn);
 
-   DRILock( screenInfo.screens[pScrn->scrnIndex], 0 );
    pMga->haveQuiescense = 1;
 
    if ( pMga->directRenderingEnabled ) {
@@ -401,8 +400,6 @@ void MGAGetQuiescenceShared( ScrnInfoPtr
    MGAEntPtr pMGAEnt = pMga->entityPrivate;
    MGAPtr pMGA2 = MGAPTR(pMGAEnt->pScrn_2);
 
-   DRILock( screenInfo.screens[pMGAEnt->pScrn_1->scrnIndex], 0 );
-
    pMga = MGAPTR(pMGAEnt->pScrn_1);
    pMga->haveQuiescense = 1;
    pMGA2->haveQuiescense = 1;
@@ -496,13 +493,24 @@ static void MGAWakeupHandler( int screen
     ScreenPtr pScreen = screenInfo.screens[screenNum];
     ScrnInfoPtr pScrn = xf86Screens[pScreen->myNum];
     MGAPtr pMga = MGAPTR(pScrn);
+    MGAEntPtr pMGAEnt;
 
     if ( xf86IsEntityShared( pScrn->entityList[0] ) 
                && pMga->DualHeadEnabled) {
+        pMGAEnt = pMga->entityPrivate;
+
+        if (pMGAEnt->directRenderingEnabled)
+            DRILock(screenInfo.screens[pMGAEnt->pScrn_1->scrnIndex], 0);
+
         MGASwapContextShared( pScreen );
     } else {
+        if (pMga->directRenderingEnabled)
+            DRILock(pScreen, 0);
+
         MGASwapContext( pScreen );
     }
+
+    pMga->haveQuiescense = 1;
 }
 
 static void MGABlockHandler( int screenNum, pointer blockData,
diff --git a/src/mga_driver.c b/src/mga_driver.c

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