drm/radeon: only apply the SS fractional workaround to RS[78]80

[ Upstream commit ae5b80d2b68eac945b124227dea34462118a6f01 ]

Looks like some RV6xx have problems with that.

bug:
https://bugs.freedesktop.org/show_bug.cgi?id=97099

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>

diff --git a/drivers/gpu/drm/radeon/atombios_crtc.c b/drivers/gpu/drm/radeon/atombios_crtc.c
index ec2c80384fe4bad25b9696288a17ee28732a168a..e0780bf1138f5381a07def0bf74518ed865ddf68 100644 (file)
--- a/drivers/gpu/drm/radeon/atombios_crtc.c
+++ b/drivers/gpu/drm/radeon/atombios_crtc.c
@@ -617,7 +617,9 @@ static u32 atombios_adjust_pll(struct drm_crtc *crtc,
                        if (radeon_crtc->ss.refdiv) {
                                radeon_crtc->pll_flags |= RADEON_PLL_USE_REF_DIV;
                                radeon_crtc->pll_reference_div = radeon_crtc->ss.refdiv;
-                               if (rdev->family >= CHIP_RV770)
+                               if (ASIC_IS_AVIVO(rdev) &&
+                                   rdev->family != CHIP_RS780 &&
+                                   rdev->family != CHIP_RS880)
                                        radeon_crtc->pll_flags |= RADEON_PLL_USE_FRAC_FB_DIV;
                        }
                }