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Date: Fri, 16 May 2008 15:25:36 +0200
From: Jan Kiszka <jan.kiszka@domain.hid>
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Subject: Re: [Xenomai-help] Serial driver and TX events
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To: Anders Blomdell <anders.blomdell@domain.hid>
Cc: xenomai-help <xenomai@xenomai.org>

Anders Blomdell wrote:
> Jan Kiszka wrote:
>> Anders Blomdell wrote:
>>> Are there any reason why the serial driver could not be changed to give an event
>>> when all characters has left the TX buffer?
>> No, I don't think so. Somehow I have the feeling someone requested this
>> feature before, but I cannot find any reference  or even code ATM.
>> However. Patch would be welcome.
> OK, I'll see what I can do. Is patch against 2.4.2 OK (pressing deadline -> I do
> not have the time to uprade right now).

Such a patch would currently apply against trunk as-is, at least /wrt
16550A - but I would take care of porting in any case.

> 
> My need for it is to make it possible to wait until all characters has left the
> FIFO (needed for autobaud detection), so perhaps a ioctl RTIOC_DRAIN (similar to
> RTIOC_PURGE) is a better choice (you decide what you prefer, and I'll try to
> implement it)

Hmm, for that particular use case I guess it shouldn't be problematic to
wait the required time after writing some probe character(s).

Otherwise, a blocking RTIOC_DRAIN sounds reasonable. That could become
an (optional) common feature of all buffering RTDM devices.

Jan

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