sl@0: // Copyright (c) 2008-2009 Nokia Corporation and/or its subsidiary(-ies).
sl@0: // All rights reserved.
sl@0: // This component and the accompanying materials are made available
sl@0: // under the terms of the License "Eclipse Public License v1.0"
sl@0: // which accompanies this distribution, and is available
sl@0: // at the URL "http://www.eclipse.org/legal/epl-v10.html".
sl@0: //
sl@0: // Initial Contributors:
sl@0: // Nokia Corporation - initial contribution.
sl@0: //
sl@0: // Contributors:
sl@0: //
sl@0: // Description:
sl@0: // e32\drivers\locmedia\dmasupport.cpp
sl@0: // 
sl@0: //
sl@0: 
sl@0: #include <kernel/kernel.h>
sl@0: #include <kernel/cache.h>
sl@0: #include "locmedia.h"
sl@0: #include "dmasupport.h"
sl@0: #include "dmasupport.inl"
sl@0: 
sl@0: #include "OstTraceDefinitions.h"
sl@0: #ifdef OST_TRACE_COMPILER_IN_USE
sl@0: #include "locmedia_ost.h"
sl@0: #ifdef __VC32__
sl@0: #pragma warning(disable: 4127) // disabling warning "conditional expression is constant"
sl@0: #endif
sl@0: #include "dmasupportTraces.h"
sl@0: #endif
sl@0: 
sl@0: #define PHYSADDR_FAULT()	Kern::Fault("TLOCDRV-PHYS-ADDR",__LINE__)
sl@0: 
sl@0: //#define __DEBUG_DMASUP__
sl@0: #ifdef __DEBUG_DMASUP__
sl@0: #define __KTRACE_DMA(p) {p;}
sl@0: #else
sl@0: #define __KTRACE_DMA(p)
sl@0: #endif
sl@0: 
sl@0: TInt DDmaHelper::iPageSize;
sl@0: TInt DDmaHelper::iPageSizeLog2;
sl@0: TInt DDmaHelper::iPageSizeMsk;
sl@0: 
sl@0: /******************************************************************************
sl@0:  DDmaHelper
sl@0:  ******************************************************************************/
sl@0: const TPhysAddr KPhysMemFragmented = KPhysAddrInvalid;
sl@0: 
sl@0: TUint32 Log2(TUint32 aVal)
sl@0: 	{	
sl@0:     __ASSERT_COMPILE(sizeof(TUint32) == 4);
sl@0: 
sl@0:     TUint32 bitPos=31;
sl@0: 
sl@0:     if(!(aVal >> 16)) {bitPos-=16; aVal<<=16;}
sl@0:     if(!(aVal >> 24)) {bitPos-=8;  aVal<<=8 ;}
sl@0:     if(!(aVal >> 28)) {bitPos-=4;  aVal<<=4 ;}
sl@0:     if(!(aVal >> 30)) {bitPos-=2;  aVal<<=2 ;}
sl@0:     if(!(aVal >> 31)) {bitPos-=1;}
sl@0:     
sl@0:     return bitPos;
sl@0: 	}
sl@0: 
sl@0: TBool IsPowerOfTwo(TInt aNum)
sl@0: //
sl@0: // Returns ETrue if aNum is a power of two
sl@0: //
sl@0: 	{
sl@0: 	return (aNum != 0 && (aNum & -aNum) == aNum);
sl@0: 	}
sl@0: 
sl@0: void DDmaHelper::ResetPageLists()
sl@0: 	{
sl@0: 	iFragLen = 0;
sl@0: 	iFragLenRemaining = 0;
sl@0: 	}
sl@0: 
sl@0: DDmaHelper::DDmaHelper()
sl@0: 	{
sl@0: 	OstTraceFunctionEntry0( DDMAHELPER_DDMAHELPER_ENTRY );
sl@0: 	iPageSize = Kern::RoundToPageSize(1);
sl@0: 	__ASSERT_ALWAYS(IsPowerOfTwo(iPageSize), PHYSADDR_FAULT());
sl@0: 	iPageSizeLog2 = Log2(iPageSize);
sl@0: 	iPageSizeMsk = iPageSize-1;
sl@0: 	OstTraceFunctionExit0( DDMAHELPER_DDMAHELPER_EXIT );
sl@0: 	}
sl@0: 
sl@0: DDmaHelper::~DDmaHelper()
sl@0: 	{
sl@0: 	OstTraceFunctionEntry0( DESTRUCTOR_DDMAHELPER_ENTRY );
sl@0: 	delete [] iPageArray;
sl@0: 	delete [] iPageList;
sl@0: 	if (iPhysicalPinObject)
sl@0: 		{
sl@0: 		NKern::ThreadEnterCS();
sl@0: 		Kern::DestroyPhysicalPinObject(iPhysicalPinObject);
sl@0: 		NKern::ThreadLeaveCS();
sl@0: 		}
sl@0: 	OstTraceFunctionExit0( DESTRUCTOR_DDMAHELPER_EXIT );
sl@0: 	}
sl@0: 
sl@0: /**
sl@0: Constructs the DDmaHelper object 
sl@0: 
sl@0: @param aLength The maximum length of data mapped by this object.
sl@0: 			   Should be a multiple of the page size 
sl@0: @param aMediaBlockSize The minimum amount data that the media can transfer in read / write operations
sl@0: @param aDmaAlignment The memory alignment required by the media devices DMA controller. (i.e. word aligned = 2)
sl@0: 
sl@0: @return KErrNone,if successful;
sl@0: 		KErrNoMemory, if unable to create Page Array's.
sl@0: */
sl@0: TInt DDmaHelper::Construct(TInt aLength, TInt aMediaBlockSize, TInt aDmaAlignment)
sl@0: 	{
sl@0: 	OstTraceFunctionEntry1( DDMAHELPER_CONSTRUCT_ENTRY, this );
sl@0: 	__ASSERT_ALWAYS(aMediaBlockSize > 0, PHYSADDR_FAULT());
sl@0: 	__ASSERT_ALWAYS(IsPowerOfTwo(aMediaBlockSize), PHYSADDR_FAULT());
sl@0: 	__ASSERT_ALWAYS(aLength > 0, PHYSADDR_FAULT());
sl@0: 	__ASSERT_ALWAYS(aLength > iPageSize, PHYSADDR_FAULT());
sl@0: 
sl@0: 	// This code assumes that the media block size (normally 512) is >= the processor's 
sl@0: 	// cache-line size (typically 32 bytes). This may not be true for future processors.
sl@0: 	// If the cache-line size was 1024, for example,  reading 512 bytes into a client's 
sl@0: 	// buffer & then calling Cache::SyncMemoryAfterDmaRead would invalidate an entire 1024 
sl@0: 	// bytes in the user's address space.
sl@0: 	TUint cacheLineSize = Cache::DmaBufferAlignment();
sl@0: 	__ASSERT_ALWAYS(IsPowerOfTwo(cacheLineSize), PHYSADDR_FAULT());
sl@0: 	if (cacheLineSize > (TUint) aMediaBlockSize)
sl@0: 	    {
sl@0: 		OstTraceFunctionExitExt( DDMAHELPER_CONSTRUCT_EXIT1, this, KErrNotSupported );
sl@0: 		return KErrNotSupported;
sl@0: 	    }
sl@0: 	
sl@0: 	//Check whether Kernel supports physical memory pinning:
sl@0: 	TInt mm = Kern::HalFunction(EHalGroupKernel, EKernelHalMemModelInfo, 0, 0) & EMemModelTypeMask;
sl@0: 	if (mm >= EMemModelTypeFlexible)
sl@0: 		{
sl@0: 		// Flexible memory model supports physical pinning for user (and Kernel) memory that
sl@0: 		// is the subject of DMA transfer.
sl@0: 		// Physical memory pinning ensures that:
sl@0: 		// - physical memory is not moved by RAM defragmentation.
sl@0: 		// - it is safe to to DMA against it or do sync cache (using new interface) even if/when
sl@0: 		// the owner of the memory (e.g. untrusted user aplication) decomits memory or panics.
sl@0: 		// For details @see Kern::PinPhysicalMemory.
sl@0: 		// Cache Sync of physically pinned memory on flexible memory model is done by:
sl@0: 		//  - Cache::SyncPhysicalMemoryBeforeDmaWrite
sl@0: 		//  - Cache::SyncPhysicalMemoryBeforeDmaRead
sl@0: 		//  - Cache::SyncPhysicalMemoryAfterDmaRead
sl@0: 		iPhysPinningAvailable = ETrue;
sl@0: 		__KTRACE_DMA(Kern::Printf("Memory model (%d) supports physical pinning\n",mm));
sl@0: 		NKern::ThreadEnterCS();
sl@0: 		TInt r=Kern::CreatePhysicalPinObject(iPhysicalPinObject);
sl@0: 		OstTraceExt2(TRACE_DMASUPPORT, DDMAHELPER_CONSTRUCT1, "Memory model=%d supports physical pinning; created Physical Pin Object with return value=%d",mm, r);
sl@0: 		NKern::ThreadLeaveCS();
sl@0: 		if (r) return r;
sl@0: 		}
sl@0: 	else
sl@0: 		{
sl@0: 		// Memory models before flexible do not support memory pinning.
sl@0: 		// The driver has to use  PrepareMemoryForDMA/ReleaseMemoryFromDMA Kernel interface 
sl@0: 		// that ensures that physical memory won't be moved by RAM defragmentation module.
sl@0: 		// However, Kernel relies on assumption that the user memory won't dissapear (e.g. by
sl@0: 		// user client closing the chunk or panics), as it would lead to Kernel crash.
sl@0: 		// For that reason, the only use case for DMA transfer into user memory is File System's
sl@0: 		// read/write buffer - as it is assumed that File System is trusted component.
sl@0: 		// To mark its buffers(s) for DMA transfer, File Sytem must call UserSvr::RegisterTrustedChunk
sl@0: 		// before DMA transfer starts.
sl@0: 		// Cache sync. operations before/after DMA transfer must be done by using the old Cache interface:
sl@0: 		//  - Cache::SyncMemoryBeforeDmaWrite
sl@0: 		//  - Cache::SyncMemoryBeforeDmaRead
sl@0: 		//  - Cache::SyncMemoryAfterDmaRead
sl@0: 		// As they all require linear address as input, these methods also rely on File System buffers
sl@0: 		// to be in valid state during sync calls.
sl@0: 		iPhysPinningAvailable = EFalse;
sl@0: 		__KTRACE_DMA(Kern::Printf("Memory model (%d) doesn't support physical pining",mm));
sl@0: 		OstTrace1(TRACE_DMASUPPORT, DDMAHELPER_CONSTRUCT2, "Memory model=%d doesn't support physical pinning",mm);
sl@0: 		iPhysicalPinObject = NULL;
sl@0: 		}
sl@0: 	
sl@0: 	iMaxPages = (aLength >> iPageSizeLog2)-1;
sl@0: 	
sl@0: 	// 2 Additional pages for page straddling
sl@0: 	iPageArray = new TPhysAddr[iMaxPages+2];
sl@0: 	if (iPageArray != NULL)
sl@0: 		{
sl@0: 		iPageList = new TPageList[iMaxPages];
sl@0: 		if (iPageList != NULL)
sl@0: 			{
sl@0: 			iMediaBlockSize = aMediaBlockSize;
sl@0: 			iMediaBlockSizeMask = TInt64(iMediaBlockSize - 1);
sl@0: 
sl@0: 			iDmaAlignment = aDmaAlignment;
sl@0: 			__KTRACE_DMA(Kern::Printf("-PHYSADDR: Construct iMaxPages(%d), MediaBlocks(%d), DMAalign(%d)",iMaxPages,iMediaBlockSize,iDmaAlignment));
sl@0: 			OstTraceExt3(TRACE_FLOW, DDMAHELPER_CONSTRUCT_EXIT2, "< KErrNone PHYSADDR: Construct iMaxPages %d MediaBlocks %d DMAalign %d", iMaxPages,iMediaBlockSize,iDmaAlignment );
sl@0: 			return KErrNone;
sl@0: 			}
sl@0: 		delete [] iPageArray; iPageArray = NULL;
sl@0: 		}
sl@0: 	
sl@0: 	iMaxPages = 0;
sl@0: 	OstTraceFunctionExitExt( DDMAHELPER_CONSTRUCT_EXIT3, this, KErrNoMemory );
sl@0: 	return KErrNoMemory;
sl@0: 	}
sl@0: 
sl@0: /**
sl@0:  * Each Read/Write request is examined to determine if the descriptor that 
sl@0:  * is referenced is mapped to a physical memory object; 
sl@0:  * if so it prepares the memory, updates the request with physical memory information
sl@0:  * and issues the request.
sl@0:  * If a request does not make use of physical memory or is not configured correctly the
sl@0:  * request is passed through without modification.
sl@0:  */
sl@0: TInt DDmaHelper::SendReceive(TLocDrvRequest& aReq, TLinAddr aLinAddress)
sl@0: 	{
sl@0: 	OstTraceFunctionEntry0( DDMAHELPER_SENDRECEIVE_ENTRY );
sl@0: 	DPrimaryMediaBase& primaryMedia = *aReq.Drive()->iPrimaryMedia;
sl@0: 	
sl@0: 	TInt reqId = aReq.Id();
sl@0: 	if (reqId != DLocalDrive::ERead && reqId != DLocalDrive::EWrite)
sl@0: 	    {
sl@0: 	    OstTrace0(TRACE_FLOW, DDMAHELPER_SENDRECEIVE_EXIT1, "< Request is not ERead or EWrite, cannot perform Direct Memory Access");
sl@0: 		return aReq.SendReceive(&primaryMedia.iMsgQ);
sl@0: 	    }
sl@0: 		
sl@0: 	if ((I64HIGH(aReq.Length()) > 0) || (aReq.Length() < iMediaBlockSize))
sl@0: 	    {
sl@0: 	    OstTrace0(TRACE_FLOW, DDMAHELPER_SENDRECEIVE_EXIT2, "< Invalid request length, cannot perform Direct Memory Access");
sl@0: 		return aReq.SendReceive(&primaryMedia.iMsgQ);
sl@0: 	    }
sl@0: 	
sl@0: 	// If more than one user thread tries to access the drive, then bail out as there is 
sl@0: 	// only one DDmaHelper object per TLocDrv. Normally this shouldn't ever happen unless
sl@0: 	// a client app accesses the drive directly using TBusLOcalDrive or the file system is 
sl@0: 	// asynchronous (i.e. there is a separate drive thread) but the file server message is 
sl@0: 	// flagged as synchronous - e.g. EFsDrive
sl@0: 	if (TInt(__e32_atomic_add_ord32(&iLockCount, 1)) > 0)	// busy ?
sl@0: 		{
sl@0: 		__KTRACE_DMA(Kern::Printf("-PHYSADDR: BUSY"));
sl@0: 		__e32_atomic_add_ord32(&iLockCount, TUint32(-1));
sl@0: 		OstTrace0(TRACE_FLOW, DDMAHELPER_SENDRECEIVE_EXIT3, "< DMA Busy");
sl@0: 		return aReq.SendReceive(&primaryMedia.iMsgQ);
sl@0: 		}
sl@0: 
sl@0: 	// make a copy of the request 
sl@0: 	iMemoryType = EUnknown;
sl@0: 	iReq = &aReq;
sl@0: 	iReqId = reqId;
sl@0: 		
sl@0: 	iReqPosClient = iReq->Pos();
sl@0: 
sl@0: 	iReqLenClient = I64LOW(iReq->Length());
sl@0: 
sl@0: 	iReqRemoteDesOffset = iReq->RemoteDesOffset();
sl@0: 	iReqFlags = iReq->Flags();
sl@0: 
sl@0: 	iRemoteThread = iReq->RemoteThread();
sl@0: 	iCurrentThread = &Kern::CurrentThread();
sl@0: 	iOwningThread = iRemoteThread ? iRemoteThread : iCurrentThread;
sl@0: 
sl@0: 	iChunk = NULL;
sl@0: 	iChunkOffset = 0;
sl@0: 	iLinAddressUser = NULL;
sl@0: 	iLenConsumed = 0;
sl@0: 
sl@0: 	// point to the start of the descriptor
sl@0: 	iLinAddressUser = aLinAddress - iReqRemoteDesOffset;
sl@0: 	
sl@0: 	// Need to check descriptors from both direct Clients (i.e. file cache, RemoteThread == NULL )
sl@0: 	// and Remote Server Clients (file server clients, RemoteThread != NULL)
sl@0: 	// Shared Memory can potentially be used by both remote server and direct clients
sl@0: 	NKern::ThreadEnterCS();
sl@0: 	iChunk = Kern::OpenSharedChunk(iOwningThread, (const TAny*) iLinAddressUser, ETrue, iChunkOffset);
sl@0: 	NKern::ThreadLeaveCS();
sl@0: 	
sl@0: 	TInt fragments = 0;
sl@0: 	TInt r;
sl@0: 	do
sl@0: 		{
sl@0: 		__KTRACE_DMA(Kern::Printf(">PHYSADDR:SendReceive() iReqLen %d; iLenConsumed %d; fragments %d",iReqLen, iLenConsumed, fragments));
sl@0: 		OstTraceExt2( TRACE_DMASUPPORT, DDMAHELPER_SENDRECEIVE1, "PHYSADDR:SendReceive() iLenConsumed=%d; fragments=%d", iLenConsumed, fragments);
sl@0: 		r = RequestStart();
sl@0: 		if (r != KErrNone)
sl@0: 			{
sl@0: 			if (iChunk)
sl@0: 				{
sl@0: 				NKern::ThreadEnterCS();
sl@0: 				Kern::ChunkClose(iChunk);
sl@0: 				iChunk = NULL;
sl@0: 				NKern::ThreadLeaveCS();
sl@0: 				}
sl@0: 			__KTRACE_DMA(Kern::Printf("<PHYSADDR:SendReceive()- r:%d",r));
sl@0: 			OstTrace1( TRACE_FLOW, DDMAHELPER_SENDRECEIVE_EXIT4, "< PHYSADDR:SendReceive() Return code %d",r);
sl@0: 			iMemoryType = EUnknown;
sl@0: 			__e32_atomic_add_ord32(&iLockCount, TUint32(-1));
sl@0: 			return fragments ? r : iReq->SendReceive(&primaryMedia.iMsgQ);
sl@0: 			}
sl@0: 		else
sl@0: 			{
sl@0: 			iReq->Flags() |= TLocDrvRequest::EPhysAddr;
sl@0: 			}
sl@0: 
sl@0: 		__KTRACE_DMA(Kern::Printf("-PHYSADDR:SendReceive() rThread %08X pos %08lX, len %d addr %08X off %08X", 
sl@0: 				iRemoteThread, iReq->Pos(), I64LOW(iReq->Length()), iLinAddressUser, iReqRemoteDesOffset));
sl@0: 		OstTraceExt4(TRACE_DMASUPPORT, DDMAHELPER_SENDRECEIVE2, "PHYSADDR:SendReceive() position=%Ld; length=%d; address=0x%x; offset=0x%x", iReq->Pos(), (TInt) I64LOW(iReq->Length()), (TUint) iLinAddressUser, (TUint) iReqRemoteDesOffset );
sl@0: 		
sl@0: 		__ASSERT_DEBUG(iReq->Length() == FragLength(), PHYSADDR_FAULT());
sl@0: 		__ASSERT_DEBUG(iReq->Length() != 0, PHYSADDR_FAULT());
sl@0: 
sl@0: 		// reinstate iValue in case overwritten by DMediaPagingDevice::CompleteRequest()
sl@0: 		iReq->iValue = iReqId;
sl@0: 		
sl@0: 		OstTrace1(TRACE_DMASUPPORT, DDMAHELPER_SENDRECEIVE3, "Dma SendReceive Start iReq=%d", iReq);
sl@0: 		r = iReq->SendReceive(&primaryMedia.iMsgQ);
sl@0: 		OstTrace1(TRACE_DMASUPPORT, DDMAHELPER_SENDRECEIVE4, "Dma SendReceive Return iReq=%d", iReq);
sl@0: 		
sl@0: 		// The media driver could potentially choose to deal with the request 
sl@0: 		// without accessing physical memory (e.g. if the data is already cached).
sl@0: 		iLenConsumed += iFragLenRemaining;
sl@0: 				
sl@0: 		RequestEnd();
sl@0: 		
sl@0: 		ResetPageLists();
sl@0: 
sl@0: 		fragments++;
sl@0: 		
sl@0: 		}
sl@0: 	while(r == KErrNone && LengthRemaining() > 0);
sl@0: 
sl@0: 	if (iChunk)		
sl@0: 		{
sl@0: 		NKern::ThreadEnterCS();
sl@0: 		Kern::ChunkClose(iChunk);
sl@0: 		iChunk = NULL;
sl@0: 		NKern::ThreadLeaveCS();
sl@0: 		}
sl@0: 	
sl@0: 	// Set remote descriptor length to iReqLenClient
sl@0: 	if (iReqId == DLocalDrive::ERead && r == KErrNone)
sl@0: 		r = UpdateRemoteDescriptorLength(iReqLenClient);
sl@0: 
sl@0: 	__KTRACE_DMA(Kern::Printf("<PHYSADDR:SendReceive()"));
sl@0: 
sl@0: 	iMemoryType = EUnknown;
sl@0: 
sl@0: 	__e32_atomic_add_ord32(&iLockCount, TUint32(-1));
sl@0: 	OstTraceFunctionExit0( DDMAHELPER_SENDRECEIVE_EXIT5 );
sl@0: 	return r;
sl@0: 	}
sl@0: 
sl@0: 
sl@0: /**
sl@0:  * Each read/write request is split into one or more DMA "fragments".
sl@0:  * The maximum size of each fragment depends on the size of iPageArray[].
sl@0:  * Subsquent calls to RequestStart maybe required to complete a request.
sl@0:  * 
sl@0:  * The physical address is checked for DMA alignment or the possibility of 
sl@0:  * eventually alignment due to mis-aligned start/end media blocks.
sl@0:  * 
sl@0:  * A DMA "fragment" can be split over a number of pages as follows :
sl@0:  * ----------------------------------------------------------
sl@0:  * |    4K    |    4K    |    4K    |    4K    |
sl@0:  * ----------------------------------------------------------
sl@0:  *      ********************************		: region to be read
sl@0:  * <----------- iFragLen ----------->
sl@0:  * 
sl@0:  * The pages may not be physically contiguous; if they are not, 
sl@0:  * then they are supplied to the media driver one contiguous 
sl@0:  * sequent at a time by GetPhysicalAddress()
sl@0:  **/
sl@0: TInt DDmaHelper::RequestStart()
sl@0: 	{
sl@0: 	OstTraceFunctionEntry1( DDMAHELPER_REQUESTSTART_ENTRY, this );
sl@0: 	__KTRACE_DMA(Kern::Printf(">PHYSADDR:RequestStart()"));
sl@0: 
sl@0: 	iIndex = 0;
sl@0: 
sl@0: 	TLinAddr startAddr = LinAddress();
sl@0: 	TInt64 startPos = iReqPosClient + iLenConsumed;
sl@0: 	TInt mediaBlockOffset = BlockOffset(startPos);
sl@0: 	TInt addrBlockOffset = BlockOffset(startAddr);
sl@0: 	TInt length = Min(LengthRemaining(), MaxFragLength());
sl@0: 
sl@0: 	iPageArrayCount = iPageListCount = 0;
sl@0: 
sl@0: 	TLinAddr firstPageStart = PageAlign(startAddr);
sl@0: 	TLinAddr lastPageStart = PageAlign(startAddr + length + iPageSize - 1);
sl@0: 	iPageArrayCount = (lastPageStart - firstPageStart + 1) >> iPageSizeLog2;
sl@0: 
sl@0: 	iMemoryType = EUnknown;
sl@0: 	iPhysAddr = KPhysMemFragmented; // Default - Mark memory as fragmented
sl@0: 
sl@0: 	//*************************************
sl@0: 	// Check Physical Page Alignment!!	
sl@0: 	//*************************************
sl@0: 	if (!IsBlockAligned(startPos))
sl@0: 		{
sl@0: 		// Will DMA align at next block alignment? such that DMA can be used
sl@0: 		TInt ofset = I64LOW((startPos + iMediaBlockSize) & (iMediaBlockSize-1));
sl@0: 		ofset = iMediaBlockSize - ofset;
sl@0: 
sl@0: 		if (!IsDmaAligned(startAddr))
sl@0: 			{			
sl@0: 			__KTRACE_DMA(Kern::Printf("<PHYSADDR:RequestStart() - not DMA Aligned pos 0x%x addr 0x%x)",I64LOW(startPos), startAddr));
sl@0: 			OstTraceExt2( TRACE_FLOW, DDMAHELPER_REQUESTSTART_EXIT1, "< KErrNotSupported Not DMA Aligned startPos %x startAddr %x", I64LOW(startPos), startAddr );
sl@0: 			return KErrNotSupported;
sl@0: 			}
sl@0: 		}
sl@0: 	else 
sl@0: 		{ //block aligned!
sl@0: 		if (!IsDmaAligned(startAddr))
sl@0: 			{
sl@0: 			__KTRACE_DMA(Kern::Printf("<PHYSADDR:RequestStart() - not DMA Aligned (0x%x)",startAddr));
sl@0: 			OstTrace1(TRACE_FLOW, DDMAHELPER_REQUESTSTART_EXIT2, "< KErrNotSupported Not DMA Aligned startAddr %x", startAddr);
sl@0: 			return KErrNotSupported;
sl@0: 			}
sl@0: 		}
sl@0: 
sl@0: 	//************************************************
sl@0: 	// Check for possible striping of RAM pages vs Media blocks
sl@0: 	// i.e. Media blocks which may straddle 2 non contiguous pages. 
sl@0: 	//************************************************
sl@0: 	if (mediaBlockOffset != addrBlockOffset)
sl@0: 		{
sl@0: 		__KTRACE_DMA(Kern::Printf("<PHYSADDR:RequestStart() - Frag / not block aligned: pos 0x%x addr 0x%x", I64LOW(startPos), startAddr));
sl@0: 		OstTraceExt2(TRACE_FLOW, DDMAHELPER_REQUESTSTART_EXIT3, "< KErrNotSupported Frag / not block aligned: startPos 0x%x startAddr 0x%x", I64LOW(startPos), startAddr );
sl@0: 		return KErrNotSupported;
sl@0: 		}
sl@0: 
sl@0: 	//************************************************
sl@0: 	// Is it File Server Cache request ?
sl@0: 	//************************************************
sl@0: 	if (iChunk == NULL &&				// Not Shared memory
sl@0: 		iRemoteThread == NULL &&		// Direct Client Request
sl@0: 		IsPageAligned(startAddr) &&
sl@0: 		IsBlockAligned(startPos) &&
sl@0: 		(iPageArrayCount > 0) )
sl@0: 		{
sl@0: 		TLinAddr firstPageAddr = PageAlign(startAddr); //ensure that it is page aligned.
sl@0: 		
sl@0: 		TInt r = KErrNone;
sl@0: 		if (iPhysPinningAvailable)
sl@0: 			{
sl@0: 			TBool readOnlyMem = (iReqId == DLocalDrive::EWrite); 
sl@0: 			r =  Kern::PinPhysicalMemory(iPhysicalPinObject,  firstPageAddr, iPageArrayCount << iPageSizeLog2,
sl@0: 					readOnlyMem, iPhysAddr, iPageArray, iMapAttr, iPageColour, iCurrentThread);
sl@0: 			}
sl@0: 		else
sl@0: 			{
sl@0: 			NKern::ThreadEnterCS();
sl@0: 			r = Kern::PrepareMemoryForDMA(iCurrentThread, (void*)firstPageAddr, iPageArrayCount << iPageSizeLog2, iPageArray);
sl@0: 			NKern::ThreadLeaveCS();
sl@0: 			}
sl@0: 		if (r != KErrNone) 
sl@0: 		    {
sl@0: 			OstTraceFunctionExitExt( DDMAHELPER_REQUESTSTART_EXIT4, this, r );
sl@0: 			return r;
sl@0: 		    }
sl@0: 
sl@0: 		iMemoryType = EFileServerChunk;
sl@0: 		
sl@0: 		__KTRACE_DMA(Kern::Printf("-PHYSADDR:RequestStart() - EFileServerChunk"));
sl@0: 		OstTrace0( TRACE_DMASUPPORT, DDMAHELPER_REQUESTSTART1, "EFileServerChunk");
sl@0: 		}
sl@0: 	//****************************
sl@0: 	// Is it shared chunk ?
sl@0: 	//****************************
sl@0: 	else if (iChunk)
sl@0: 		{
sl@0: 		// calculate chunk offset of start of first page
sl@0: 		TInt offset = iChunkOffset + iReqRemoteDesOffset+ iLenConsumed;
sl@0: 				
sl@0: 		TInt r = Kern::ChunkPhysicalAddress(iChunk, offset, length, iLinAddressKernel, iMapAttr, iPhysAddr, iPageArray);
sl@0: 		
sl@0: 		if (r < KErrNone)
sl@0: 		    {
sl@0: 			OstTraceFunctionExitExt( DDMAHELPER_REQUESTSTART_EXIT5, this, r );
sl@0: 			return r;  // 0 = Contiguous Memory, 1 = Fragmented/Dis-Contiguous Memory
sl@0: 		    }
sl@0: 			
sl@0: 		iMemoryType = ESharedChunk;
sl@0: 		
sl@0: 		__KTRACE_DMA(Kern::Printf("-PHYSADDR:RequestStart() - ESharedChunk"));
sl@0: 		OstTrace0( TRACE_DMASUPPORT, DDMAHELPER_REQUESTSTART2, "ESharedChunk");
sl@0: 		}
sl@0: 	else
sl@0: 		{
sl@0: 		__KTRACE_DMA(Kern::Printf("<PHYSADDR:RequestStart() - EUnknown"));
sl@0: 		OstTraceFunctionExitExt( DDMAHELPER_REQUESTSTART_EXIT6, this, KErrNotFound );
sl@0: 		return KErrNotFound;
sl@0: 		}
sl@0: 
sl@0: 	SetFragLength(length);
sl@0: 	
sl@0: 	//************************************************
sl@0: 	// Build Contiguous Page list
sl@0: 	//************************************************
sl@0: 	BuildPageList();
sl@0: 	
sl@0: 	//************************************************
sl@0: 	// Set up request parameters for this fragment 
sl@0: 	//************************************************
sl@0: 	iReq->Length() = MAKE_TINT64(0, length);
sl@0: 	iReq->Pos() = iReqPosClient + iLenConsumed;
sl@0: 	iReq->RemoteDesOffset() = iReqRemoteDesOffset + iLenConsumed;
sl@0: 	// restore EAdjusted flag to ensure iReq->Pos() is adjusted correctly
sl@0: 	iReq->Flags()&= ~TLocDrvRequest::EAdjusted;
sl@0: 	iReq->Flags()|= (iReqFlags & TLocDrvRequest::EAdjusted);
sl@0: 
sl@0: 	//************************************************
sl@0: 	// Sync memory
sl@0: 	//************************************************
sl@0: 	__KTRACE_DMA(Kern::Printf(">SYNC-PHYSADDR:addr 0x%x len %d", startAddr, length));
sl@0: 	OstTraceExt2(TRACE_DMASUPPORT, DDMAHELPER_REQUESTSTART3, "startAddr=0x%x length=%d", (TUint) startAddr, length );
sl@0: 
sl@0: 	// Only sync whole blocks: it is assumed that the media driver will transfer 
sl@0: 	// partial start and end blocks without DMA
sl@0: 
sl@0: 	TInt startBlockPartialLen = IsBlockAligned(startPos) ? 0 : iMediaBlockSize - BlockOffset(startPos);
sl@0: 	TInt blockLen = (TInt) BlockAlign(length - startBlockPartialLen);
sl@0: 
sl@0: 	if (iReqId == DLocalDrive::EWrite)
sl@0: 		{
sl@0: 		if (iMemoryType == ESharedChunk)
sl@0: 			{
sl@0: 			Cache::SyncMemoryBeforeDmaWrite(iLinAddressKernel+startBlockPartialLen, blockLen, iMapAttr);
sl@0: 			}
sl@0: 		else // (iMemoryType == EFileServerChunk)
sl@0: 			{
sl@0: 			if (iPhysPinningAvailable)
sl@0: 				Cache::SyncPhysicalMemoryBeforeDmaWrite(iPageArray, iPageColour, startBlockPartialLen, blockLen, iMapAttr);
sl@0: 			else
sl@0: 				Cache::SyncMemoryBeforeDmaWrite(startAddr+startBlockPartialLen, blockLen);
sl@0: 			}
sl@0: 		}
sl@0: 	else
sl@0: 		{
sl@0: 		if (iMemoryType == ESharedChunk)
sl@0: 			Cache::SyncMemoryBeforeDmaRead(iLinAddressKernel, length, iMapAttr);
sl@0: 		else // (iMemoryType == EFileServerChunk)
sl@0: 			{
sl@0: 			if (iPhysPinningAvailable)
sl@0: 				Cache::SyncPhysicalMemoryBeforeDmaRead(iPageArray, iPageColour, 0, length, iMapAttr);
sl@0: 			else
sl@0: 				Cache::SyncMemoryBeforeDmaRead(startAddr, length);
sl@0: 			}
sl@0: 		}
sl@0: 
sl@0: 	__KTRACE_DMA(Kern::Printf("<PHYSADDR:RequestStart()"));
sl@0: 
sl@0: 	OstTraceFunctionExitExt( DDMAHELPER_REQUESTSTART_EXIT7, this, KErrNone );
sl@0: 	return KErrNone;
sl@0: 	}
sl@0: 
sl@0: /**
sl@0:  * After read requests this method synchronous the current physical memory in use.
sl@0:  */
sl@0: void DDmaHelper::RequestEnd()
sl@0: 	{
sl@0: 	OstTraceFunctionEntry0( DDMAHELPER_REQUESTEND_ENTRY );
sl@0: 	__KTRACE_DMA(Kern::Printf(">PHYSADDR:RequestEnd()"));
sl@0: 
sl@0: 
sl@0: 	__ASSERT_DEBUG(iReqId == DLocalDrive::ERead || iReqId == DLocalDrive::EWrite, PHYSADDR_FAULT());
sl@0: 	__ASSERT_DEBUG(iMemoryType == ESharedChunk || iMemoryType == EFileServerChunk, PHYSADDR_FAULT());
sl@0: 
sl@0: 	TInt length = FragLength();	// len of data just transferred
sl@0: 	TLinAddr startAddr = LinAddress() - length;
sl@0: 
sl@0: 	// Sync the memory : but not if the media driver has decided to transfer ALL the data using IPC rather than DMA.
sl@0: 	// It is assumed that the media driver will transfer partial start & end blocks using IPC, but it may also choose 
sl@0: 	// to use IPC for the ENTIRE fragment when read/writing at the end of the media (see medmmc.cpp)
sl@0: 	if (iFragLenRemaining < length && iReqId == DLocalDrive::ERead)
sl@0: 		{
sl@0: 		TInt64 startPos = iReq->Pos();
sl@0: 		TInt startBlockPartialLen = IsBlockAligned(startPos) ? 0 : iMediaBlockSize - BlockOffset(startPos);
sl@0: 		TInt blockLen = (TInt) BlockAlign(length - startBlockPartialLen);
sl@0: 
sl@0: 		if (iMemoryType == ESharedChunk)
sl@0: 			{
sl@0: 			Cache::SyncMemoryAfterDmaRead(iLinAddressKernel + startBlockPartialLen, blockLen);
sl@0: 			}
sl@0: 		else // (iMemoryType == EFileServerChunk)
sl@0: 			{
sl@0: 			if (iPhysPinningAvailable)
sl@0: 				Cache::SyncPhysicalMemoryAfterDmaRead(iPageArray, iPageColour, startBlockPartialLen, blockLen, iMapAttr);
sl@0: 			else
sl@0: 				Cache::SyncMemoryAfterDmaRead(startAddr + startBlockPartialLen, blockLen);
sl@0: 			}
sl@0: 
sl@0: 		}
sl@0: 	ReleasePages(PageAlign(startAddr));
sl@0: 	OstTraceFunctionExit0( DDMAHELPER_REQUESTEND_EXIT );
sl@0: 	}
sl@0: 
sl@0: /**
sl@0:  * For File Server chunks this method releases the current physical memory in use.
sl@0:  * 
sl@0:  * @see Kern::ReleaseMemoryFromDMA()
sl@0:  */
sl@0: void DDmaHelper::ReleasePages(TLinAddr aAddr)
sl@0: 	{
sl@0: 	OstTraceFunctionEntry1( DDMAHELPER_RELEASEPAGES_ENTRY, this );
sl@0: 	if (iMemoryType == EFileServerChunk)
sl@0: 		{
sl@0: 		__KTRACE_DMA(Kern::Printf(">PHYSADDR():ReleasePages thread (0x%x) aAddr(0x%08x) size(%d) iPageArray(0x%x)",iCurrentThread, aAddr, (iPageArrayCount << iPageSizeLog2), iPageArray));
sl@0: 		OstTraceExt3( TRACE_DMASUPPORT, DDMAHELPER_RELEASEPAGES, "ReleasePages aAddr=0x%x; size=%d; iPageArray-0x%x", (TUint) aAddr, (iPageArrayCount << iPageSizeLog2), (TUint) iPageArray);
sl@0: 
sl@0: 		TInt r;
sl@0: 		if (iPhysPinningAvailable)
sl@0: 			{
sl@0: 			r = Kern::UnpinPhysicalMemory(iPhysicalPinObject);
sl@0: 			}
sl@0: 		else
sl@0: 			{
sl@0: 			NKern::ThreadEnterCS();
sl@0: 			r = Kern::ReleaseMemoryFromDMA(iCurrentThread, (void*) aAddr, iPageArrayCount << iPageSizeLog2, iPageArray);
sl@0: 			NKern::ThreadLeaveCS();
sl@0: 			}
sl@0: 		__ASSERT_ALWAYS(r == KErrNone, PHYSADDR_FAULT());
sl@0: 		}		
sl@0: 	OstTraceFunctionExit1( DDMAHELPER_RELEASEPAGES_EXIT, this );
sl@0: 	}
sl@0: 
sl@0: /**
sl@0:  * Utility method which examines the page array, compiling adjacent pages into contiguous fragments
sl@0:  * and populating iPageList with said fragments.
sl@0:  */
sl@0: void DDmaHelper::BuildPageList()
sl@0: 	{
sl@0: 	OstTraceFunctionEntry1( DDMAHELPER_BUILDPAGELIST_ENTRY, this );
sl@0: 	iPageListCount = 0;
sl@0: 	
sl@0: 	if (iPhysAddr != KPhysMemFragmented)
sl@0: 		{
sl@0: 		__KTRACE_DMA(Kern::Printf(">PHYSADDR:BuildPageList() - Contiguous Memory"));
sl@0: 		OstTrace0( TRACE_DMASUPPORT, DDMAHELPER_BUILDPAGELIST1, "Contiguous Memory");
sl@0: 		// Only one entry required.
sl@0: 		iPageList[0].iAddress = iPhysAddr;
sl@0: 		iPageList[0].iLength = FragLength();
sl@0: 		iPageListCount = 1;
sl@0: 		}
sl@0: 	else
sl@0: 		{
sl@0: 		__KTRACE_DMA(Kern::Printf(">PHYSADDR:BuildPageList() - Dis-Contiguous Memory"));
sl@0: 		OstTrace0( TRACE_DMASUPPORT, DDMAHELPER_BUILDPAGELIST2, "Dis-Contiguous Memory");
sl@0: 		TInt offset;
sl@0: 		
sl@0: 		offset = PageOffset(iChunkOffset + iReqRemoteDesOffset+ iLenConsumed);
sl@0: 		iPageList[0].iAddress = iPageArray[0]+offset;
sl@0: 		iPageList[0].iLength  = iPageSize-offset;
sl@0: 		
sl@0: 		TInt lengthRemaining = FragLength() - iPageList[0].iLength;
sl@0: 		
sl@0: 		TInt i =1;
sl@0:         for( ; i < iPageArrayCount; i++)
sl@0:             {
sl@0:             //Check if RAM pages are physically adjacent
sl@0:             if ((iPageArray[i-1] + PageSize()) == iPageArray[i])
sl@0:                 {
sl@0:                 // Adjacent pages - just add length
sl@0:                 iPageList[iPageListCount].iLength += PageSize();             
sl@0:                 }
sl@0:             else     	
sl@0:                 {
sl@0:                 // Not Adjacent, start new Memory fragment
sl@0:                 iPageListCount++;
sl@0:                 iPageList[iPageListCount].iAddress = iPageArray[i];
sl@0:                 iPageList[iPageListCount].iLength  = iPageSize;
sl@0:                 }
sl@0:             
sl@0:             lengthRemaining -= PageSize();
sl@0:             if (lengthRemaining < 0)
sl@0:             	{
sl@0:             	// Last page, re-adjust length for odd remainder.            	
sl@0:             	iPageList[iPageListCount].iLength += lengthRemaining;
sl@0:             	break;
sl@0:             	}
sl@0:             }
sl@0:         
sl@0:         iPageListCount++;
sl@0: 		}
sl@0: 
sl@0: //#ifdef __DEBUG_DMASUP__
sl@0: //	for (TInt m=0; m<iPageListCount; m++)
sl@0: //		__KTRACE_DMA(Kern::Printf("-PHYSADDR:BuildPageList() [%d]: %08X l:%d", m, iPageList[m].iAddress, iPageList[m].iLength));
sl@0: //#endif
sl@0: 	OstTraceFunctionExit1( DDMAHELPER_BUILDPAGELIST_EXIT, this );
sl@0: 	}
sl@0: 
sl@0: 
sl@0: /**
sl@0:  * Returns Address and Length of next contiguous Physical memory fragment
sl@0:  * 
sl@0:  * @param aAddr On success, populated with the Physical Address of the next fragment.
sl@0:  * @param aLen  On success, populated with the length in bytes of the next fragment.
sl@0:  * 
sl@0:  * @return KErrNone, if successful;
sl@0:  * 		   KErrNoMemory, if no more memory fragments left.
sl@0:  */
sl@0: TInt DDmaHelper::GetPhysicalAddress(TPhysAddr& aAddr, TInt& aLen)
sl@0: 	{
sl@0: 	OstTraceFunctionEntry1( DUP1_DDMAHELPER_GETPHYSICALADDRESS_ENTRY, this );
sl@0: 	if (iIndex >= iPageListCount)
sl@0: 		{
sl@0: 		__KTRACE_DMA(Kern::Printf(">PHYSADDR:GetPhysD() [%d], PageListCount:%d", iIndex, iPageListCount));
sl@0: 		OstTraceExt2(TRACE_DMASUPPORT, DDMAHELPER_GETPHYSICALADDRESS1, "GetPhysD() [%d]; iPageCountList=%d", iIndex, iPageListCount );
sl@0: 		aAddr = 0;
sl@0: 		aLen = 0;
sl@0: 		OstTraceFunctionExitExt( DUP1_DDMAHELPER_GETPHYSICALADDRESS_EXIT1, this, KErrGeneral );
sl@0: 		return KErrGeneral;
sl@0: 		}
sl@0: 	
sl@0: 	aAddr = iPageList[iIndex].iAddress;
sl@0: 	aLen = iPageList[iIndex].iLength;
sl@0: 	iLenConsumed+= aLen;
sl@0: 	iFragLenRemaining-= aLen;
sl@0: 	
sl@0: 	__KTRACE_DMA(Kern::Printf(">PHYSADDR:GetPhysD() [%d] addr:0x%08X, l:%d; Used:%d, Left:%d", iIndex, aAddr, aLen, iLenConsumed, iFragLenRemaining));
sl@0: 	OstTraceExt5(TRACE_DMASUPPORT, DDMAHELPER_GETPHYSICALADDRESS2, "GetPhysD() [%d]; address=0x%x; length=%d; iLenConsumed=%d; iFragLenRemaining=%d", iIndex, (TUint) aAddr, aLen, iLenConsumed, iFragLenRemaining);
sl@0: 	__ASSERT_DEBUG(aLen >= 0, PHYSADDR_FAULT());
sl@0: 
sl@0: 	iIndex++;  //Move index to next page
sl@0: 
sl@0: 	OstTraceFunctionExitExt( DDMAHELPER_GETPHYSICALADDRESS_EXIT2, this, KErrNone );
sl@0: 	return KErrNone;
sl@0: 	}
sl@0: 
sl@0: 
sl@0: #ifdef __DEMAND_PAGING__
sl@0: /**
sl@0:  * Returns Address and Length of next contiguous Physical memory. 
sl@0:  * Static function specifically for Demand Paging support
sl@0:  * 
sl@0:  * @param aReq  TLocDrvRequest from which physical 
sl@0:  * @param aAddr Populated with the Physical Address of the Request aReq.
sl@0:  * @param aLen  Populated with the length in bytes of the memory.
sl@0:  * 
sl@0:  * @return KErrNone 
sl@0:  */
sl@0: TInt DDmaHelper::GetPhysicalAddress(TLocDrvRequest& aReq, TPhysAddr& aAddr, TInt& aLen)
sl@0: 	{
sl@0: 	OstTraceFunctionEntry0( DDMAHELPER_GETPHYSICALADDRESS_ENTRY );
sl@0: 	__ASSERT_DEBUG( (aReq.Flags() & TLocDrvRequest::ETClientBuffer) == 0,  PHYSADDR_FAULT());
sl@0: 	TLinAddr linAddr = (TLinAddr) aReq.RemoteDes();
sl@0: 	TInt& offset = aReq.RemoteDesOffset();
sl@0: 	TLinAddr currLinAddr = linAddr + offset;
sl@0: 	TInt reqLen = I64LOW(aReq.Length());
sl@0: 	__ASSERT_DEBUG(I64HIGH(aReq.Length()) == 0,  PHYSADDR_FAULT());
sl@0: 
sl@0: 	aAddr = Epoc::LinearToPhysical(currLinAddr);
sl@0: 
sl@0: 	// Set the initial length to be the length remaining in this page or the request length (whichever is shorter).
sl@0: 	// If there are subsequent pages, we then need to determine whether they are contiguous
sl@0: 	aLen = Min( (TInt) (PageAlign(currLinAddr+iPageSize) - currLinAddr), reqLen - offset);
sl@0: 
sl@0: 	__ASSERT_DEBUG(aLen > 0,  PHYSADDR_FAULT());
sl@0: 	
sl@0: 	TPhysAddr currPhysPageAddr = PageAlign((TLinAddr) aAddr);
sl@0: 
sl@0: 	offset+= aLen;
sl@0: 
sl@0: 
sl@0: 	while (offset < reqLen)
sl@0: 		{
sl@0: 		TPhysAddr nextPhysPageAddr = Epoc::LinearToPhysical(linAddr + offset);
sl@0: 		__ASSERT_DEBUG(PageOffset((TLinAddr) nextPhysPageAddr) == 0,  PHYSADDR_FAULT());
sl@0: 
sl@0: 		if (nextPhysPageAddr != currPhysPageAddr + iPageSize)
sl@0: 			break;
sl@0: 		
sl@0: 		currPhysPageAddr = nextPhysPageAddr;
sl@0: 
sl@0: 		TInt len = Min(iPageSize, reqLen - offset);
sl@0: 		offset+= len;
sl@0: 		aLen+= len;
sl@0: 		}
sl@0: 
sl@0: 
sl@0: 	__KTRACE_DMA(Kern::Printf(">PHYSADDR:DP:GetPhysS(), linAddr %08X, physAddr %08X, len %x reqLen %x", linAddr + offset, aAddr, aLen, reqLen));
sl@0: 	OstTraceExt4(TRACE_DEMANDPAGING, DDMAHELPER_GETPHYSICALADDRESS_DP, "linAddr=0x%x; physAddr=0x%x; length=0x%x; reqLen=0x%x", linAddr + offset, aAddr, aLen, reqLen);
sl@0: 	OstTraceFunctionExit0( DDMAHELPER_GETPHYSICALADDRESS_EXIT );
sl@0: 	return KErrNone;
sl@0: 	}
sl@0: #endif	// (__DEMAND_PAGING__)
sl@0: 
sl@0: 
sl@0: /**
sl@0:  * Modifies the current requests remote descriptor length
sl@0:  * 
sl@0:  * @param aLength Length in bytes to which the descriptor is to be set.
sl@0:  * 
sl@0:  * @return KErrNone, if successful;
sl@0:  * 		   KErrBadDescriptor, if descriptor is corrupted;
sl@0:  * 		   otherwise one of the other system wide error codes.
sl@0:  */
sl@0: 
sl@0: TInt DDmaHelper::UpdateRemoteDescriptorLength(TInt aLength)
sl@0: 	{
sl@0: 	OstTraceFunctionEntryExt( DDMAHELPER_UPDATEREMOTEDESCRIPTORLENGTH_ENTRY, this );
sl@0: 	__KTRACE_DMA(Kern::Printf(">PHYSADDR:UpDesLen(%d)",aLength));
sl@0: 
sl@0: 	// Restore request Id (overwritten by KErrNone return code) to stop ASSERT in WriteRemote
sl@0: 	iReq->Id() = DLocalDrive::ERead;
sl@0: 
sl@0: 	// restore caller's descriptor offset
sl@0: 	iReq->RemoteDesOffset() = iReqRemoteDesOffset;
sl@0: 
sl@0: 	// Write a zero length descriptor at the end such that the descriptors length is correctly updated.
sl@0: 	TPtrC8 zeroDes(NULL, 0);
sl@0: 	TInt r = iReq->WriteRemote(&zeroDes, aLength);
sl@0: 
sl@0: 	// restore return code	
sl@0: 	iReq->iValue = KErrNone;
sl@0: 
sl@0: 	OstTraceFunctionExitExt( DDMAHELPER_UPDATEREMOTEDESCRIPTORLENGTH_EXIT, this, r );
sl@0: 	return r;
sl@0: 	}
sl@0: