Date: Thu, 27 May 2004 18:05:32 +0400 From: Roman Kurakin <rik@cronyx.ru> To: Bruce Evans <bde@zeta.org.au> Cc: cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/dev/uart uart_dev_ns8250.c Message-ID: <40B5F5AC.4080500@cronyx.ru> In-Reply-To: <20040527123826.R8527@gamplex.bde.org> References: <200405262159.i4QLx1cQ072334@repoman.freebsd.org> <20040527123826.R8527@gamplex.bde.org>
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Bruce Evans wrote: >On Wed, 26 May 2004, Thomas Moestl wrote: > > > >>tmm 2004/05/26 14:59:01 PDT >> >> FreeBSD src repository >> >> Modified files: >> sys/dev/uart uart_dev_ns8250.c >> Log: >> It seems that clearing the MCR_IE bit in the modem control register >> does not reliably prevent the triggering of interrupts for all supported >> configurations. Thus, the FIFO size probe could cause an interrupt, >> which could lead to an interrupt storm in the shared interrupt case. >> >> > >s/It seems that clearing/Clearing/. Clearing MCR_IE disables the device's >line driver for the irq. At least on old i386 isa systems, the line driver >is normally connected to a tri-state latch which floats high due to a weak >pullup when all its inputs are disabled. So "disabling" interrupts by > > As far as I know some modern UARTS do not support this feature. For example, Exar 17C158. rik
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