[PATCH] drm/radeon/kms: use frac fb div on APUs

[alexdeucher at gmail.com]

From: Alex Deucher <alexander.deucher at amd.com>

Seems to be more stable on certain monitors.

Fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=48880

Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
Cc: stable at vger.kernel.org
---
 drivers/gpu/drm/radeon/atombios_crtc.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/radeon/atombios_crtc.c b/drivers/gpu/drm/radeon/atombios_crtc.c
index b5ff1f7..c5c31e0 100644
--- a/drivers/gpu/drm/radeon/atombios_crtc.c
+++ b/drivers/gpu/drm/radeon/atombios_crtc.c
@@ -575,6 +575,9 @@ static u32 atombios_adjust_pll(struct drm_crtc *crtc,
 
 		if (rdev->family < CHIP_RV770)
 			pll->flags |= RADEON_PLL_PREFER_MINM_OVER_MAXP;
+		/* use frac fb div on APUs */
+		if (ASIC_IS_DCE41(rdev) || ASIC_IS_DCE61(rdev))
+			pll->flags |= RADEON_PLL_USE_FRAC_FB_DIV;
 	} else {
 		pll->flags |= RADEON_PLL_LEGACY;
 
-- 
1.7.7.5