viafb: fix IGA1 modesetting on VX900

Even if the documentation calls this bit "Reserved" it has to be set
to 0 for correct modesetting on IGA1.

Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Cc: stable@vger.kernel.org

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/video/via/hw.c b/drivers/video/via/hw.c
index 8bdf80e270e2..8497727d66de 100644
--- a/drivers/video/via/hw.c
+++ b/drivers/video/via/hw.c
@@ -1810,6 +1810,9 @@ static void hw_init(void)
                 break;
         }
 
+        /* magic required on VX900 for correct modesetting on IGA1 */
+        via_write_reg_mask(VIACR, 0x45, 0x00, 0x01);
+
         /* probably this should go to the scaling code one day */
         via_write_reg_mask(VIACR, 0xFD, 0, 0x80); /* VX900 hw scale on IGA2 */
         viafb_write_regx(scaling_parameters, ARRAY_SIZE(scaling_parameters));