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SubjectRe: [PATCH v3] Enable A20 using KBC for some MSI laptops to fix S3 resume
Date
On Tuesday 11 December 2012 20:07:50 H. Peter Anvin wrote:
> On 12/11/2012 10:59 AM, Ondrej Zary wrote:
> > As I said before, the BIOS probably breaks on resume before any Linux
> > code is executed. So any fix must be done before suspending.
>
> Well, that code should be independent of A20, being in low memory, but
> if the BIOS itself crashes, then that's... yeah.
>
> > I hate quirks too. A general solution would be to always enable A20 using
> > KBC (if KBC is present) but that's probably not acceptable.
>
> I don't see why not. If so we could just do it as part of the
> initialization of the i8042 driver.

Something like this? (It works.)

diff --git a/drivers/input/serio/i8042-x86ia64io.h b/drivers/input/serio/i8042-x86ia64io.h
index d6cc77a..0807ac7 100644
--- a/drivers/input/serio/i8042-x86ia64io.h
+++ b/drivers/input/serio/i8042-x86ia64io.h
@@ -921,6 +921,7 @@ static int __init i8042_platform_init(void)
int retval;

#ifdef CONFIG_X86
+ u8 a20_on = 0xdf;
/* Just return if pre-detection shows no i8042 controller exist */
if (!x86_platform.i8042_detect())
return -ENODEV;
@@ -960,6 +961,13 @@ static int __init i8042_platform_init(void)

if (dmi_check_system(i8042_dmi_dritek_table))
i8042_dritek = true;
+
+ /*
+ * A20 was already enabled during early kernel init. But some buggy
+ * BIOSes (in MSI Laptops) require A20 to be enabled using 8042 to
+ * resume from S3. So we do it here and hope that nothing breaks.
+ */
+ i8042_command(&a20_on, 0x10d1);
#endif /* CONFIG_X86 */

return retval;
--
Ondrej Zary

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