[PATCH 4.4 061/146] drm/mgag200: Black screen fix for G200e rev 4

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mathieu Larouche <mathieu.larou...@matrox.com>

commit d3922b69617b62bb2509936b68301f837229d9f0 upstream.

- Fixed black screen for some resolutions of G200e rev4
- Fixed testm & testn which had predetermined value.

Reported-by: Jan Beulich <jbeul...@suse.com>

Signed-off-by: Mathieu Larouche <mathieu.larou...@matrox.com>
Signed-off-by: Dave Airlie <airl...@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/gpu/drm/mgag200/mgag200_mode.c |   10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/mgag200/mgag200_mode.c
+++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
@@ -194,7 +194,7 @@ static int mga_g200se_set_plls(struct mg
                        }
                }
 
-               fvv = pllreffreq * testn / testm;
+               fvv = pllreffreq * (n + 1) / (m + 1);
                fvv = (fvv - 800000) / 50000;
 
                if (fvv > 15)
@@ -214,6 +214,14 @@ static int mga_g200se_set_plls(struct mg
        WREG_DAC(MGA1064_PIX_PLLC_M, m);
        WREG_DAC(MGA1064_PIX_PLLC_N, n);
        WREG_DAC(MGA1064_PIX_PLLC_P, p);
+
+       if (mdev->unique_rev_id >= 0x04) {
+               WREG_DAC(0x1a, 0x09);
+               msleep(20);
+               WREG_DAC(0x1a, 0x01);
+
+       }
+
        return 0;
 }