Changeset 82403 in vbox for trunk/src/VBox

Timestamp:

Dec 5, 2019 12:08:56 AM (5 years ago)

Author:

vboxsync

Message:

DevHDA/hdaRegWriteSDCTL: Don't take the virtual-sync clock lock unless we're likely to need it. We only need it if DMA state changes to RUN. It is bad to do unnecessary work while sitting on that lock, in addition, less locking+unlocking saves time too. bugref:9218

File:

• trunk/src/VBox/Devices/Audio/DevHDA.cpp (modified) (2 diffs)

trunk/src/VBox/Devices/Audio/DevHDA.cpp

@@ -1239 +1239 @@
     const bool fReset    = RT_BOOL(u32Value & HDA_SDCTL_SRST);
 
-    /**
-     * @todo r=bird: Must reduce the time we holding the virtual sync
-     *               clock lock here!
-     */
-    DEVHDA_UNLOCK(pDevIns, pThis);
-    DEVHDA_LOCK_BOTH_RETURN(pDevIns, pThis, pStream, VINF_IOM_R3_MMIO_WRITE);
+    /* If the run bit is set, we take the virtual-sync clock lock as well so we
+       can safely update timers via hdaR3TimerSet if necessary.   We need to be
+       very careful with the fInReset and fInRun indicators here, as they may
+       change during the relocking if we need to acquire the clock lock. */
+    const bool fNeedVirtualSyncClockLock = (u32Value & (HDA_SDCTL_RUN | HDA_SDCTL_SRST)) == HDA_SDCTL_RUN
+                                        && (HDA_REG_IND(pThis, iReg) & HDA_SDCTL_RUN) == 0;
+    if (fNeedVirtualSyncClockLock)
+    {
+        DEVHDA_UNLOCK(pDevIns, pThis);
+        DEVHDA_LOCK_BOTH_RETURN(pDevIns, pThis, pStream, VINF_IOM_R3_MMIO_WRITE);
+    }
 
     const bool fInRun    = RT_BOOL(HDA_REG_IND(pThis, iReg) & HDA_SDCTL_RUN);
@@ -1396 +1401 @@
     }
 
-    VBOXSTRICTRC rc = hdaRegWriteU24(pDevIns, pThis, iReg, u32Value);
-
-    PDMDevHlpTimerUnlockClock(pDevIns, pStream->hTimer); /* Caller will unlock pThis->CritSect. */ /** @todo r=bird: Move this up. */
-    return rc;
+    if (fNeedVirtualSyncClockLock)
+        PDMDevHlpTimerUnlockClock(pDevIns, pStream->hTimer); /* Caller will unlock pThis->CritSect. */
+
+    return hdaRegWriteU24(pDevIns, pThis, iReg, u32Value);
 #else  /* !IN_RING3 */
     RT_NOREF(pDevIns, pThis, iReg, u32Value);