Re: [PATCH v3] Enable A20 using KBC for some MSI laptops to fix S3 resume

["H. Peter Anvin" <hpa@zytor.com>]

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On 11/05/2012 12:35 PM, Ondrej Zary wrote:
> On Friday 26 October 2012 10:56:44 Ondrej Zary wrote:
>> Some MSI laptop BIOSes are broken - INT 15h code uses port 92h to enable
>> A20 line but resume code assumes that KBC was used.
>> The laptop will not resume from S3 otherwise but powers off after a while
>> and then powers on again stuck with a blank screen.
>>
>> Fix it by enabling A20 using KBC. Affected laptop list and DMI data are
>> from bug reports at Ubuntu Launchpad.
>>
>> Also add kernel parameter to easily activate this quirk on any system.
>>
>> Only compile tested. The original patch was tested with EX600 and PR200.
>>
>> Fixes https://bugzilla.kernel.org/show_bug.cgi?id=12878
> 
> The bug was marked as RESOLVED CODE_FIX but I wonder what happened to this 
> patch. Was it applied? Or is someone working on a better way to fix this 
> problem?
> 

Sorry, I managed to forget about this.

Is there any way you could test this patch by any chance?

I would be a lot happier if this works as a general solution rather than
relying on a quirk...

	-hpa


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>From 5513340abd845eaa28fe2394f7e0296599f2d9e7 Mon Sep 17 00:00:00 2001
From: "H. Peter Anvin" <hpa@linux.intel.com>
Date: Mon, 10 Dec 2012 13:17:48 -0800
Subject: [PATCH] x86, suspend: Run A20 test on resume

If A20 is disabled on resume, we may have to explicitly enable it.
Rather than creating a bunch of ad hoc code, use the same code we
would on system startup.

Note: the startup code implicitly assumes BIOS, specifically that int
$0x15 is enabled.  However, for non-BIOS platforms to have A20 closed
on resume seems extremely unlikely, since pretty much all non-BIOS
firmware run in 32- or 64-bit mode.

Reported-by: Ondrej Zary <linux@rainbow-software.org>
Link: http://lkml.kernel.org/r/201210240847.52417.linux@rainbow-software.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
---
 arch/x86/realmode/rm/Makefile   | 2 +-
 arch/x86/realmode/rm/a20.c      | 1 +
 arch/x86/realmode/rm/wakemain.c | 3 +++
 3 files changed, 5 insertions(+), 1 deletion(-)
 create mode 100644 arch/x86/realmode/rm/a20.c

diff --git a/arch/x86/realmode/rm/Makefile b/arch/x86/realmode/rm/Makefile
index 8869287..7e2ff68 100644
--- a/arch/x86/realmode/rm/Makefile
+++ b/arch/x86/realmode/rm/Makefile
@@ -10,7 +10,7 @@
 always := realmode.bin realmode.relocs
 
 wakeup-objs	:= wakeup_asm.o wakemain.o video-mode.o
-wakeup-objs	+= copy.o bioscall.o regs.o
+wakeup-objs	+= copy.o bioscall.o regs.o a20.o
 # The link order of the video-*.o modules can matter.  In particular,
 # video-vga.o *must* be listed first, followed by video-vesa.o.
 # Hardware-specific drivers should follow in the order they should be
diff --git a/arch/x86/realmode/rm/a20.c b/arch/x86/realmode/rm/a20.c
new file mode 100644
index 0000000..e71d518
--- /dev/null
+++ b/arch/x86/realmode/rm/a20.c
@@ -0,0 +1 @@
+#include "../../boot/a20.c"
diff --git a/arch/x86/realmode/rm/wakemain.c b/arch/x86/realmode/rm/wakemain.c
index 91405d5..6e0d548 100644
--- a/arch/x86/realmode/rm/wakemain.c
+++ b/arch/x86/realmode/rm/wakemain.c
@@ -79,4 +79,7 @@ void main(void)
 		probe_cards(0);
 		set_mode(wakeup_header.video_mode);
 	}
+
+	/* If A20 is closed, fix now */
+	enable_a20();
 }
-- 
1.7.11.7