#112 doc. Change error return value to 255 of GetEndpointPollInterval…

…. Fix another code line with always-failing pollinterval test. Determine input direction differently if format not supported.
Wouter1 · Apr 28, 2019 · d8c570b · d8c570b
1 parent 43539c0
commit d8c570b
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Showing 3 changed files with 20 additions and 15 deletions.
diff --git a/src/EMUUSBAudio/EMUUSBAudioEngine.cpp b/src/EMUUSBAudio/EMUUSBAudioEngine.cpp
@@ -1488,25 +1488,25 @@ IOReturn EMUUSBAudioEngine::performFormatChangeInternal (IOAudioStream *audioStr
 
     if (audioStream == usbInputStream.audioStream || sampleRateChanged)
     {
-        UInt8	newDirection = usbAudio->GetIsocEndpointDirection (usbInputStream.interfaceNumber, newAlternateSettingID);
-        if (FALSE == usbAudio->VerifySampleRateIsSupported(usbInputStream.interfaceNumber, newAlternateSettingID, sampleRate.whole)) {
-            // find an alternative if requested rate not supported.
+        UInt8	newDirection;
+        if (usbAudio->VerifySampleRateIsSupported(usbInputStream.interfaceNumber, newAlternateSettingID, sampleRate.whole)) {
+            newDirection = usbAudio->GetIsocEndpointDirection (usbInputStream.interfaceNumber, newAlternateSettingID);
+            ReturnIf (newDirection != usbInputStream.streamDirection, kIOReturnError);
+        } else {
+            // sample rate is not supported on input side. Find alternative.
             // #112 it seems this code is for 0204 if someone switches to output 4 channels,
             // in which case there is no 4 channels input. So let's just try 2 channels here
+            newDirection = usbInputStream.streamDirection;
             newAlternateSettingID = usbAudio->FindAltInterfaceWithSettings (usbInputStream.interfaceNumber, 2, newFormat->fBitDepth, sampleRate.whole);
             mPollInterval = (UInt32) (1 << ((UInt32) usbAudio->GetEndpointPollInterval(usbInputStream.interfaceNumber, newAlternateSettingID, newDirection) -1));
-            if ((1 != mPollInterval) && (8 != mPollInterval)) {
+            ReturnIf ( (1 != mPollInterval) && (8 != mPollInterval), kIOReturnError);
                 // disallow selection of endpoints with sub ms polling interval
                 //NB - assumes that sub ms device will not use a poll interval of 1 (every microframe)
-                newAlternateSettingID = 255;
-            }
-            debugIOLog ("%d channel %d bit @ %d Hz is not supported. Suggesting alternate setting %d", newFormat->fNumChannels,
+
+            debugIOLog ("direction %d, %d channel %d bit @ %d Hz is not supported. Suggesting alternate setting %d", newDirection, newFormat->fNumChannels,
                         newFormat->fBitDepth, sampleRate.whole, newAlternateSettingID);
-
-            ReturnIf (255 == newAlternateSettingID, kIOReturnError);
         }
 
-        ReturnIf (newDirection != usbInputStream.streamDirection, kIOReturnError);
         debugIOLog ("++about to set input : ourInterfaceNumber = %d & newAlternateSettingID = %d", usbInputStream.interfaceNumber, newAlternateSettingID);
         beginConfigurationChange();
 
@@ -1538,7 +1538,9 @@ IOReturn EMUUSBAudioEngine::performFormatChangeInternal (IOAudioStream *audioStr
         if (FALSE == usbAudio->VerifySampleRateIsSupported(mOutput.interfaceNumber, newAlternateSettingID, sampleRate.whole)) {
             newAlternateSettingID = usbAudio->FindAltInterfaceWithSettings (mOutput.interfaceNumber, newFormat->fNumChannels, newFormat->fBitDepth, sampleRate.whole);
             mPollInterval = (UInt32) (1 << ((UInt32) usbAudio->GetEndpointPollInterval(mOutput.interfaceNumber, newAlternateSettingID, newDirection) -1));
-            if ((1 != mPollInterval) || (8 != mPollInterval)) {// disallow selection of endpoints with sub ms polling interval NB - assumes that sub ms device will not use a poll interval of 1 (every microframe)
+            if ((1 != mPollInterval) && (8 != mPollInterval)) {
+                // disallow selection of endpoints with sub ms polling interval NB -
+                // assumes that sub ms device will not use a poll interval of 1 (every microframe)
                 newAlternateSettingID = 255;
             }
             debugIOLog ("%d channel %d bit @ %d Hz is not supported. Suggesting alternate setting %d", newFormat->fNumChannels,

diff --git a/src/EMUUSBAudio/USBAudioObject.cpp b/src/EMUUSBAudio/USBAudioObject.cpp
@@ -147,9 +147,10 @@ UInt8 EMUUSBAudioConfigObject::FindAltInterfaceWithSettings(UInt8 interfaceNum,
 	UInt8			potentialAltInterface = 1;
 	UInt8			theAltInterface = 255;
 
+	debugIOLogPC("Searching for alternative for interface %d, %d channels, rate %d", interfaceNum, numChannels, sampleRate);
     // clumsy loop, straightforward write-out is lot smaller and readable. FIXME?
 	while(potentialAltInterface != 255) {
-		if((GetFormat(interfaceNum, potentialAltInterface) & 0x0FFF) != 0) {	// Make sure it's not an undefined format
+		if((GetFormat(interfaceNum, potentialAltInterface) & 0x0FFF) != 0) {	// Make sure it's a defined format
 			potentialAltInterface = FindNextAltInterfaceWithNumChannels(interfaceNum, potentialAltInterface, numChannels);
 			if(255 == potentialAltInterface) {
 				debugIOLogPC("Undefined format! No alternate setting ID for interface %d, %d channels", interfaceNum, numChannels);
@@ -316,14 +317,14 @@ UInt8 EMUUSBAudioConfigObject::GetEndpointPollInterval(UInt8 interfaceNum, UInt8
 	EMUUSBAudioStreamObject*	stream = GetStreamObject(interfaceNum, altInterfaceNum);
     if (!stream) {
         IOLog("Bug? EMUUSBAudioConfigObject::GetEndpointPollInterval stream not opening");
-        return 1; // can we cancel the whole thing?
+        return 255;
     }
 
     UInt8	address = stream->GetIsocEndpointAddress(direction);
     EMUUSBEndpointObject*	endpoint = stream->GetEndpointByAddress(address);
     if (!endpoint) {
         IOLog("Bug? EMUUSBAudioConfigObject::GetEndpointPollInterval no endpoint");
-        return 1; // can we cancel the whole thing?
+        return 255;
     }
 
     pollInterval = endpoint->GetPollInt();

diff --git a/src/EMUUSBAudio/USBAudioObject.h b/src/EMUUSBAudio/USBAudioObject.h
@@ -960,7 +960,9 @@ class EMUUSBAudioConfigObject : public OSObject {
 	UInt16							GetFormat (UInt8 interfaceNum, UInt8 altInterfaceNum);
 	UInt32							GetHighestSampleRate (UInt8 interfaceNum, UInt8 altInterfaceNum);
 	UInt32							GetEndpointMaxPacketSize(UInt8 interfaceNum, UInt8 altInterfaceNum, UInt8 address);
-    /*! get endpoint poll interval (bInterval), 1=every microframe, 2=every 2 microframes, 3=every 4 microframes, 4=every frame, etc */
+    /*! @return endpoint poll interval (bInterval), 1=every microframe, 2=every 2 microframes, 3=every 4 microframes, 4=8micro=1 full frame, etc.
+     Nomally the endpoint interval is computed as 1<<(pollinterval-1). If an error occurs, this returns 255.
+     */
 	UInt8							GetEndpointPollInterval(UInt8 interfaceNum, UInt8 altInterfaceNum, UInt8 direction);
 
 	UInt8							GetIsocAssociatedEndpointAddress (UInt8 interfaceNum, UInt8 altInterfaceNum, UInt8 address);