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From: "Luck, Tony" <tony.luck@intel.com>
To: Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: Keith Owens <kaos@sgi.com>,
	linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org
Subject: Re: KDB blindly reads keyboard port
Date: Fri, 29 Sep 2006 18:01:10 +0000	[thread overview]
Message-ID: <20060929180110.GA4021@intel.com> (raw)
In-Reply-To: <200609291057.41529.bjorn.helgaas@hp.com>

On Fri, Sep 29, 2006 at 10:57:41AM -0600, Bjorn Helgaas wrote:
>   acpi_parse_fadt: acpi_kbd_controller_present 0

The logic in the kernel seems backwards here though.  We start
by assuming there is a keyboard, then when parsing the FADT
we reset this assumption if the BAF_8042_KEYBOARD_CONTROLLER
bit isn't set.  Which in turn forced SGI to include some
workaround code for their older PROM (which doesn't provide
the FADT table).

There's also a risk that if some code might get added that
runs before we parse FADT that could be confused into thinking
that the keyboard is present.

Wouldn't it be simpler/better to assume there is no keyboard until
we find positive evidence that there is one?

-Tony

WARNING: multiple messages have this Message-ID (diff)
From: "Luck, Tony" <tony.luck@intel.com>
To: Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: Keith Owens <kaos@sgi.com>,
	linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org
Subject: Re: KDB blindly reads keyboard port
Date: Fri, 29 Sep 2006 11:01:10 -0700	[thread overview]
Message-ID: <20060929180110.GA4021@intel.com> (raw)
In-Reply-To: <200609291057.41529.bjorn.helgaas@hp.com>

On Fri, Sep 29, 2006 at 10:57:41AM -0600, Bjorn Helgaas wrote:
>   acpi_parse_fadt: acpi_kbd_controller_present 0

The logic in the kernel seems backwards here though.  We start
by assuming there is a keyboard, then when parsing the FADT
we reset this assumption if the BAF_8042_KEYBOARD_CONTROLLER
bit isn't set.  Which in turn forced SGI to include some
workaround code for their older PROM (which doesn't provide
the FADT table).

There's also a risk that if some code might get added that
runs before we parse FADT that could be confused into thinking
that the keyboard is present.

Wouldn't it be simpler/better to assume there is no keyboard until
we find positive evidence that there is one?

-Tony

  reply	other threads:[~2006-09-29 18:01 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-09-26 19:54 KDB blindly reads keyboard port Bjorn Helgaas
2006-09-26 19:54 ` Bjorn Helgaas
2006-09-27  2:45 ` Keith Owens
2006-09-27  2:45   ` Keith Owens
2006-09-27 11:57   ` Matthew Wilcox
2006-09-27 11:57     ` Matthew Wilcox
2006-09-27 22:11   ` Bjorn Helgaas
2006-09-27 22:11     ` Bjorn Helgaas
2006-09-29  2:18 ` Keith Owens
2006-09-29  2:18   ` Keith Owens
2006-09-29 16:57   ` Bjorn Helgaas
2006-09-29 16:57     ` Bjorn Helgaas
2006-09-29 18:01     ` Luck, Tony [this message]
2006-09-29 18:01       ` Luck, Tony
2006-09-29 18:58       ` Bjorn Helgaas
2006-09-29 18:58         ` Bjorn Helgaas
2006-11-10  4:23 ` Keith Owens
2006-11-10  4:23   ` Keith Owens
2006-11-10  4:28   ` Matthew Wilcox
2006-11-10  4:28     ` Matthew Wilcox
2006-11-10  6:15 ` Keith Owens
2006-11-10  6:15   ` Keith Owens
2006-11-16  4:02 ` Keith Owens
2006-11-16  4:02   ` Keith Owens
2006-11-16 16:28   ` Bjorn Helgaas
2006-11-16 16:28     ` Bjorn Helgaas

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