Date: Mon, 3 Jul 1995 02:44:21 +1000 From: Bruce Evans <bde@zeta.org.au> To: ache@astral.msk.su, bde@zeta.org.au, cvs-sys@freefall.cdrom.com Subject: Re: cvs commit: src/sys/i386/isa sio.c Message-ID: <199507021644.CAA18626@godzilla.zeta.org.au>
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>>> Fight with hanging modems continued: >>> return EIO after t_timeout expired instead infinite looping in "siotx" >>> in comparam, consuming CPU time. >>Why does this loop occur? It can't happen with working 8250..16550 >>... >Bruce, I don't know, *why* it occurs, I am not hardware expert. This means that your fix is probably sub-optimal. What makes the problem go away? close() doesn't do anything to unwedge the transmitter bits, and open() fails early when it calls comparam(). >I only know that it *occurs* sometimes and my goal is to make >modem pool which can work without human eye when possible. >This thing cures by dropping DTR, EIO here usualy cause close >and DTR drop. I am not think, that it is CTS hang, symptom >are: modem TX light is on forever (sio waits, when TX done >forever too). Joerg f.e. send me "thanx" for this fix, he >have this situation too (it means that it isn't only my hardware). Please submit a full bug report before hiding the problem. For this bug I would like to know at least: 1) state of all UART registers. 2) what happens when interrupts are disabled so the driver can't possibly keep feeding the transmitter. Brucehome | help
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