wince 下usb key传输问题

tongwxy 2008-3-26 15:41 楼主

大家好，最近在我一个ce下的usb key的驱动开发，出现这样的问题，麻烦大家给个意见。问题描述如下：
驱动中我采用xxx_read 和xxx_write来响应读写操作，也就是采用流设备的方式。读写操作中，写操作不会有问题，而读操作中一次最多读取到64 byte的数据（设备一次只能发送64byte），所以在少于64byte的字节读操作时不会有问题，但是因为ukey涉及到rsa密钥对产生，它的数据大于64byte，也就是说一次传输无法完成。问题就出现在这里，在生成rsa密钥对的时候，由于数据量大，会出现设备死等的现象。
跟踪到ohci层发现，在每次设备传输完成的时候调用的CheckForDoneTransfers中，发现64个byte的数据已经到了td缓冲区，并且已经缓存起来。这个时候程序不再往下执行。跟正常操作的进行比较过后发现，在64 byte的数据写进td缓冲区后，就不再有后续的操作。问题也是在下面这个CheckForDoneTransfersThread函数中产生的
ULONG CHCCAera::CheckForDoneTransfersThread( )
{
SetKMode(TRUE);

DEBUGMSG( ZONE_TRANSFER && ZONE_VERBOSE, (TEXT("+CHCCAera::CheckForDoneTransfersThread\n")) );

DEBUGCHK( m_hCheckForDoneTransfersEvent != NULL );

while ( !m_fCheckTransferThreadClosing ) {
      WaitForSingleObject( m_hCheckForDoneTransfersEvent, INFINITE );
      if ( m_fCheckTransferThreadClosing ) {
         break;
      }

      // Must be set when this thread is signalled but under stress conditions
      // it could get temporarily unset by the time we get here. If that
      // happens then we just wait for the event to get signalled again.
      TDLINK pTD;
      pTD.td = (P_TD) InterlockedExchange((LPLONG)&m_pDoneHead, 0L);
      while (pTD.td) {
         CPipe * pTDPipe;
         if (pTD.td->bfIsIsoch) {
            pTDPipe =  pTD.itd->pPipe;
            ASSERT(pTD.itd->pTransfer->GetPipe() == pTDPipe);
         }
         else {
            pTDPipe = pTD.td->pPipe ;
            ASSERT( pTD.td->pTransfer->GetPipe() == pTDPipe);
         }
         // these fields all have the same offsets for TDs and ITDs
         if (pTD.td->bfDiscard) {
            // the transfer has been aborted already and completed elsewhere
            DEBUGMSG(ZONE_WARNING, (TEXT("CPipe::CFDT DISCARDING td %08x nxt %08x xfr %08x\n"), pTD.td, pTD.td->paNextTd.td,pTDPipe));
            pTD = pTD.td->paNextTd;
            continue;
         }
         DEBUGMSG(ZONE_TRANSFER && ZONE_VERBOSE, (TEXT("CPipe::CFDT td %08x nxt %08x xfr %08x\n"), pTD.td, pTD.td->paNextTd,pTDPipe));
         // advance pTD first because it will get freed if it's the last TD of the transfer
         // see notes above for why we can and want to advance multiple
         TDLINK pNextTD =  pTD.td->paNextTd; // same offset as for itd
RETAILMSG(N,(TEXT("TO CheckForDoneTransfers\r\n")));
         pTDPipe->CheckForDoneTransfers(pTD);
         pTD = pNextTD;
      }
}
DEBUGMSG( ZONE_TRANSFER && ZONE_VERBOSE, (TEXT("-CHCCAera::CheckForDoneTransfersThread\n")) );
return 0;
}
无法再进入这个while (pTD.td)循环，而且也等不到hCheckForDoneTransfersEvent这个事件。不知道出现这样的问题，该有什么好的方法解决，多谢大家指教！！