[PATCH-ACPI]: Fix broken EC Object on some Acer notebooks

[Joshua C.]

I have an Acer which has a borken Bios. Actually the DSDT has a
nonexisting Method which gives a kernel panic. Bugs 10237 and 8953 on
bugzilla.kernel.org were filed about this problem and Yakui Zhao made
a patch for this. I don't know when this  is going to end in the
mainstream kernel but till then we can have it in the fedora kernel.
Any objections?

The patch (I've tested this with current FC8 and FC9 - works well):
----------------------
Subject:ACPI: Ignore AE_NOT_FOUND error of EC _REG method and continue
to initialize EC
From: Zhao Yakui <yakui.zhao at intel.com>

On some broken BIOS the ACPI object in EC _REG method can't be found in
ACPI namespace, which causes that the AE_NOT_FOUND status code is returned by
the EC _REG object. In such case the EC device can't be initialized correctly,
which causes that battery/AC adapter can't work normally. As the EC address
space handler is not removed and the memory pointed by its input argument is
already free, sometimes the kernel will also be panic when EC internal register
is still accessed. But the windows can work well on such broken BIOS.

Maybe it will be reasonable that OS ignores the AE_NOT_FOUND error
returned by the EC _REG object and continues to initialize EC device
for some broken BIOS. Of course the warning message will be printed.
For example: the ACPI object in EC _REG method can't be found and status error
code is AE_NOT_FOUND.

http://bugzilla.kernel.org/show_bug.cgi?id=8953
http://bugzilla.kernel.org/show_bug.cgi?id=10237

Signed-off-by: Zhao Yakui <yakui.zhao at intel.com>
Signed-off-by: Lin Ming <ming.m.lin at intel.com>

---
 drivers/acpi/ec.c |   15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

Index: linux-2.6/drivers/acpi/ec.c
===================================================================
--- linux-2.6.orig/drivers/acpi/ec.c
+++ linux-2.6/drivers/acpi/ec.c
@@ -835,8 +835,19 @@ static int ec_install_handlers(struct ac
 						    &acpi_ec_space_handler,
 						    NULL, ec);
 	if (ACPI_FAILURE(status)) {
-		acpi_remove_gpe_handler(NULL, ec->gpe, &acpi_ec_gpe_handler);
-		return -ENODEV;
+		if (status == AE_NOT_FOUND) {
+			/*
+			 * Maybe OS fails in evaluating the _REG object.
+			 * The AE_NOT_FOUND error will be ignored and OS
+			 * continue to initialize EC.
+			 */
+			printk(KERN_ERR "Fail in evaluating _REG object."
+				" It is broken BIOS.\n");
+		} else {
+			acpi_remove_gpe_handler(NULL, ec->gpe,
+				&acpi_ec_gpe_handler);
+			return -ENODEV;
+		}
 	}

 	ec->handlers_installed = 1;