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Date:      Tue, 09 Dec 2008 09:57:20 -0500
From:      Mike Tancsa <mike@sentex.net>
To:        Marcel Moolenaar <xcllnt@mac.com>
Cc:        freebsd-current@freebsd.org
Subject:   Re: uart vs sio differences ?
Message-ID:  <200812091457.mB9EvLSD047534@lava.sentex.ca>
In-Reply-To: <7.1.0.9.0.20081208173515.13f62e88@sentex.net>
References:  <200812081621.mB8GLMxB041498@lava.sentex.ca> <ED8BC24F-EAC3-4266-AF54-4C6262DDC156@mac.com> <200812081906.mB8J6oha042222@lava.sentex.ca> <CF6E0ACA-CCFA-4A35-A88F-C95484309A78@mac.com> <200812082049.mB8KnHSN042710@lava.sentex.ca> <84A7F176-5A74-48AC-859A-C0D4C7CBCB48@mac.com> <7.1.0.9.0.20081208173515.13f62e88@sentex.net>

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At 05:39 PM 12/8/2008, Mike Tancsa wrote:

>What it appears to be is that as long as data is coming in, even at 
>1200bps, the ioctl FIONREAD returns zero and an actual read does not 
>return any data until there is either a pause in the data coming in 
>or possibly when we do a xmit/write at which point the accumulated 
>data is available for us to read.
>
>We dont know if this is due to the hardware fifo or something in the 
>driver itself.

OK, I think we found the issue!

http://www.freebsd.org/cgi/query-pr.cgi?pr=121421

Not sure if the semantics are exactly right, but adding

hint.uart.0.flags="0x100"
hint.uart.1.flags="0x100"
hint.uart.2.flags="0x100"
hint.uart.3.flags="0x100"

to device.hints fixed the issue!

The next question-- is there a way to do this with the ucom driver as 
well ?  We are seeing the same issue with it.

         ---Mike 




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