Hi Folks,
In SerialRead function in MdeModulePkg/Universal/SerialDxe/SerialIo.c,
it seems 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.
As SerialPortLib is a simple library implementation, I think it is
better to improve SerialIoDxe driver instead of SerialPortLib.
Please let me know your comments about this.
Thanks and regards,
Gary (Heyi Guo)
EFI_STATUS
EFIAPI
SerialRead (
IN EFI_SERIAL_IO_PROTOCOL *This,
IN OUT UINTN *BufferSize,
OUT VOID *Buffer
)
{
UINTN Count;
Count = 0;
if (SerialPortPoll ()) {
Count = SerialPortRead (Buffer, *BufferSize);
}
if (Count != *BufferSize) {
*BufferSize = Count;
return EFI_TIMEOUT;
}
return EFI_SUCCESS;
}
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