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Message-ID: <86802c440707250945gbea89f8l85db11eab0ebffdd@mail.gmail.com>
Date: Wed, 25 Jul 2007 09:45:28 -0700
From: "Yinghai Lu" <yhlu.kernel@gmail.com>
To: "Bjorn Helgaas" <bjorn.helgaas@hp.com>
Subject: Re: commit 7e92b4fc34 - x86, serial: convert legacy COM ports to platform devices - broke my serial console
Cc: "Jeff Garzik" <jeff@garzik.org>,
       "Maciej W. Rozycki" <macro@linux-mips.org>,
       "=?ISO-8859-1?Q?S=E9bastien_Dugu=E9?=" <sebastien.dugue@bull.net>,
       linux-kernel <linux-kernel@vger.kernel.org>,
       "Andrew Morton" <akpm@linux-foundation.org>,
       "Linus Torvalds" <torvalds@linux-foundation.org>
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On 7/25/07, Bjorn Helgaas <bjorn.helgaas@hp.com> wrote:
> On Wednesday 25 July 2007 09:57:47 am Yinghai Lu wrote:
> > On 7/25/07, Bjorn Helgaas <bjorn.helgaas@hp.com> wrote:
> > > On Tuesday 24 July 2007 10:27:26 pm Yinghai Lu wrote:
> > > > or we can make legacy_serial.force=1 is default at this point.
> > >
> > > At which point?  We already do the legacy probe if there are no
> > > PNP devices.  Do you mean we should also do the legacy probe if
> > > there are PNP devices, but no serial devices were found?  That
> > > might be reasonable to do, but wouldn't have prevented the problem
> > > on Sebastien's machine, because his machine *does* have PNP UARTs.
> >
> > but still could have problem. if the system does not have any uart,
> > and So we can not find that in DSDT...and we add legacy again...that
> > is not right.
>
> I'm sorry, I don't understand what you're saying.
>
> The behavior with my patch is: If we have PNPBIOS or ACPI, and it
> does not describe any UARTs, we assume the box has no UARTs.  If we
> don't have PNPBIOS or ACPI, we blindly probe for legacy UARTs.
>
> What behavior are you suggesting?

*** If we have PNPBIOS or ACPI, and it  does describe any UARTs, we
assume the box has no other legacy UARTs.
*** If we have PNPBIOS or ACPI, and it  does not describe any UARTs,
we blindly probe for legacy UARTs. ----------in case old box DSDT
doesn't have PNP0501 there in DSDT.
If we don't have PNPBIOS or ACPI, we blindly probe for legacy UARTs.

YH