On 01/18/2016 05:55 AM, Laszlo Ersek wrote:
On 01/18/16 12:41, Ryan Harkin wrote:
>On 18 January 2016 at 11:33, Laszlo Ersek<ler...@redhat.com> wrote:
>>On 01/18/16 11:24, Zeng, Star wrote:
>>>[...]
>>>
>>>>>
>>>>>The above analysis is very clear, thanks. I am a little concern about if
>>>>>the code changes below follow the comments in the code.
>>>>>
>>>>>In Terminal.c:
>>>>> //
>>>>> // Set the timeout value of serial buffer for
>>>>> // keystroke response performance issue
>>>>> //
>>>>>In TerminalConIn.c:
>>>>> //
>>>>> // if current timeout value for serial device is not identical with
>>>>> // the value saved in TERMINAL_DEV structure, then recalculate the
>>>>> // timeout value again and set serial attribute according to this
>>>>>value.
>>>>> //
>>>
>>>Any comments about above concern?
>>
>>Not really.
>>
>>I don't know what the purpose of the Timeout calculation is (what is the
>>"keystroke response performance issue"?), but in any case, it is a good
>>sign that TerminalDxe sets*some* Timeout explicitly.
>>
>>Plus, it has worked reliably until now, so we shouldn't change the
>>Timeout argument.
>>
>
>I think "reliably" is a bit generous;-) The most common complaint I
>get about EDK2 is that it can't handle more than a FIFO's worth of
>pasted characters on the serial port.
I tend to think this comes, at least partly, from the fact that UEFI
doesn't do interrupt-driven drivers. There's timer based polling (in
drivers), and there are busy loops (in applications, I guess).
I think you'll see the same behavior with network packet reception.
I said "reliably" beause in my environment I've had practically zero
issues with the serial terminal (beyond the one, very lacking, textual
resolution list -- but I patched that for myself permanently).
Thanks
Laszlo
Can't you just enable hardware flow control (RTS/CTS) on the UART?
--
Brian J. Johnson
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