drm/mgag200: Black screen fix for G200e rev 4

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

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

Signed-off-by: Mathieu Larouche <mathieu.larouche@matrox.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 9 insertions, 1 deletions

diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
index 14e64e08909e..d347dca17267 100644
--- a/drivers/gpu/drm/mgag200/mgag200_mode.c
+++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
@@ -182,7 +182,7 @@ static int mga_g200se_set_plls(struct mga_device *mdev, long clock)
                         }
                 }
 
-                fvv = pllreffreq * testn / testm;
+                fvv = pllreffreq * (n + 1) / (m + 1);
                 fvv = (fvv - 800000) / 50000;
 
                 if (fvv > 15)
@@ -202,6 +202,14 @@ static int mga_g200se_set_plls(struct mga_device *mdev, long clock)
         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;
 }