Star, 3 minor comments below. Thanks/Ray
> -----Original Message----- > From: Zeng, Star > Sent: Friday, August 4, 2017 4:29 PM > To: [email protected] > Cc: Zeng, Star <[email protected]>; Heyi Guo <[email protected]>; Ni, > Ruiyu <[email protected]>; Laszlo Ersek <[email protected]> > Subject: [PATCH] MdeModulePkg SerialDxe: Process timeout consistently in > SerialRead > > https://lists.01.org/pipermail/edk2-devel/2017-July/012385.html > reported the timeout processing in SerialRead is not consistent. > > Since SerialPortPoll only checks the status of serial port and returns > immediately, and SerialPortRead does not really implement a time out > mechanism and will always wait for enough input, it will cause below results: > 1. If there is no serial input at all, this interface will return timeout > immediately without any waiting; 2. If there is A characters in serial port > FIFO, > and caller requires > A+1 characters, it will wait until a new input is coming and timeout > will not really occur. > > This patch is to update SerialRead() to check SerialPortPoll() and read data > through SerialPortRead() one byte by one byte, and check timeout against > mSerialIoMode.Timeout if no input. > > Cc: Heyi Guo <[email protected]> > Cc: Ruiyu Ni <[email protected]> > Cc: Laszlo Ersek <[email protected]> > Contributed-under: TianoCore Contribution Agreement 1.0 > Signed-off-by: Star Zeng <[email protected]> > --- > MdeModulePkg/Universal/SerialDxe/SerialIo.c | 18 ++++++++++++++++-- > 1 file changed, 16 insertions(+), 2 deletions(-) > > diff --git a/MdeModulePkg/Universal/SerialDxe/SerialIo.c > b/MdeModulePkg/Universal/SerialDxe/SerialIo.c > index d2383e56dd8f..43d33dba0c2a 100644 > --- a/MdeModulePkg/Universal/SerialDxe/SerialIo.c > +++ b/MdeModulePkg/Universal/SerialDxe/SerialIo.c > @@ -465,11 +465,25 @@ SerialRead ( > ) > { > UINTN Count; > + UINTN TimeOut; > > Count = 0; > > - if (SerialPortPoll ()) { > - Count = SerialPortRead (Buffer, *BufferSize); > + while (Count < *BufferSize) { > + TimeOut = 0; > + while (TimeOut < mSerialIoMode.Timeout) { > + if (SerialPortPoll ()) { > + break; > + } > + gBS->Stall (10); 1. can you use EFI_TIMER_PERIOD_MICROSECONDS(1)? > + TimeOut += 10; 2. TImeOut++? > + } > + if (TimeOut >= mSerialIoMode.Timeout) { 3. if (TimeOut == ...) { ? > + break; > + } > + SerialPortRead (Buffer, 1); > + Count++; > + Buffer = (VOID *) ((UINT8 *) Buffer + 1); > } > > if (Count != *BufferSize) { > -- > 2.7.0.windows.1 _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
