drm/radeon: don't use fractional dividers on RS[78]80 if SS is enabled

[ Upstream commit 9ef8537e68941d858924a3eacee5a1945767cbab ]

Seems to cause problems for some older hardware. Kudos to Thom Kouwenhoven
for working a lot with the PLLs and figuring this out.

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>
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 2f2e50a0feb4e23fe47379738768ade87a38ad79..ec2c80384fe4bad25b9696288a17ee28732a168a 100644 (file)
--- a/drivers/gpu/drm/radeon/atombios_crtc.c
+++ b/drivers/gpu/drm/radeon/atombios_crtc.c
@@ -586,7 +586,8 @@ static u32 atombios_adjust_pll(struct drm_crtc *crtc,
                if (ASIC_IS_DCE41(rdev) || ASIC_IS_DCE61(rdev) || ASIC_IS_DCE8(rdev))
                        radeon_crtc->pll_flags |= RADEON_PLL_USE_FRAC_FB_DIV;
                /* use frac fb div on RS780/RS880 */
-               if ((rdev->family == CHIP_RS780) || (rdev->family == CHIP_RS880))
+               if (((rdev->family == CHIP_RS780) || (rdev->family == CHIP_RS880))
+                   && !radeon_crtc->ss_enabled)
                        radeon_crtc->pll_flags |= RADEON_PLL_USE_FRAC_FB_DIV;
                if (ASIC_IS_DCE32(rdev) && mode->clock > 165000)
                        radeon_crtc->pll_flags |= RADEON_PLL_USE_FRAC_FB_DIV;
@@ -616,7 +617,7 @@ 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 (ASIC_IS_AVIVO(rdev))
+                               if (rdev->family >= CHIP_RV770)
                                        radeon_crtc->pll_flags |= RADEON_PLL_USE_FRAC_FB_DIV;
                        }
                }