Date: Wed, 20 May 1998 10:44:44 -0700 From: Mike Smith <mike@smith.net.au> To: Bruce Evans <bde@zeta.org.au> Cc: mike@smith.net.au, current@FreeBSD.ORG, grog@lemis.com, hardware@FreeBSD.ORG, tarkhil@asteroid.svib.ru Subject: Re: IWill and sio, again and again Message-ID: <199805201744.KAA01041@dingo.cdrom.com> In-Reply-To: Your message of "Thu, 21 May 1998 04:22:51 %2B1000." <199805201822.EAA22099@godzilla.zeta.org.au>
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> >> The port worked fine on the system I debugged it on. > > > >Do you mean to say that you've assessed the problem with the ACER UART > >(or the PIC arrangement used with it)? What is your prognosis? > > No, I only worked around the problem on one IWill system. The PIC (or > something beteween the UART and the PIC) apparently latches rising edges > of IRQ signals even for IRQs that are masked in the PIC. Is this perhaps related to the 'serialized IRQ protocol' that the ACER UART claims to support? Some more research indicates that this is a "new feature" in the TX and LX chipsets. The descriptions I've been able to find of this so far seem to indicate that it might fit the bill. Look for it in the PIIX4 documentation, if you have that. You may need to pester Acer for a copy of the 513X datasheet as well. > >The inference here is that the attach assumes some port state that is > >not achieved by the normal probe. If we were to use the PnP BIOS data > >to determine the port's configuration and ignored the probe, it would > >be interesting to know if the attach would result in a working port. > > It should not-work even for non-IWill UARTs, since the attach assumes > certain values in the cfcr, ier and mcr registers. That sounds like "I agree". How much effort would be required to make the attach assume a completely indeterminate ground state, predicated simply on knowing that the port is present? -- \\ Sometimes you're ahead, \\ Mike Smith \\ sometimes you're behind. \\ mike@smith.net.au \\ The race is long, and in the \\ msmith@freebsd.org \\ end it's only with yourself. \\ msmith@cdrom.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hardware" in the body of the message
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