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Subject[014/104] viafb: correct sync polarity for OLPC DCON
3.1-stable review patch.  If anyone has any objections, please let me know.


From: Daniel Drake <>

commit a32839696a8eef813a1aff604fbad9a32dff6c95 upstream.

While the OLPC display appears to be able to handle either positive
or negative sync, the Display Controller only recognises positive sync.

This brings viafb (for XO-1.5) in line with lxfb (for XO-1) and
fixes a recent regression where the XO-1.5 DCON could no longer be
frozen. Thanks to Florian Tobias Schandinat for helping identify
the fix.

Test case: from a vt,
echo 1 > /sys/devices/platform/dcon/freeze
should cause the current screen contents to freeze, rather than garbage being

Signed-off-by: Daniel Drake <>
Signed-off-by: Florian Tobias Schandinat <>
Signed-off-by: Greg Kroah-Hartman <>

drivers/video/via/share.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/video/via/share.h
+++ b/drivers/video/via/share.h
@@ -557,8 +557,8 @@
#define M1200X720_R60_VSP POSITIVE

/* 1200x900@60 Sync Polarity (DCON) */
-#define M1200X900_R60_HSP NEGATIVE
-#define M1200X900_R60_VSP NEGATIVE
+#define M1200X900_R60_HSP POSITIVE
+#define M1200X900_R60_VSP POSITIVE

/* 1280x600@60 Sync Polarity (GTF Mode) */
#define M1280x600_R60_HSP NEGATIVE

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