1 files changed, 14 insertions, 0 deletions

diff --git a/drivers/gpu/drm/radeon/atombios_crtc.c b/drivers/gpu/drm/radeon/atombios_crtc.c
index 577239a24fd5..977f5c20ef1b 100644
--- a/drivers/gpu/drm/radeon/atombios_crtc.c
+++ b/drivers/gpu/drm/radeon/atombios_crtc.c
@@ -534,6 +534,20 @@ static u32 atombios_adjust_pll(struct drm_crtc *crtc,
                                         pll->algo = PLL_ALGO_LEGACY;
                                         pll->flags |= RADEON_PLL_PREFER_CLOSEST_LOWER;
                                 }
+                                /* There is some evidence (often anecdotal) that RV515 LVDS
+                                 * (on some boards at least) prefers the legacy algo.  I'm not
+                                 * sure whether this should handled generically or on a
+                                 * case-by-case quirk basis.  Both algos should work fine in the
+                                 * majority of cases.
+                                 */
+                                if ((radeon_encoder->active_device & (ATOM_DEVICE_LCD_SUPPORT)) &&
+                                    (rdev->family == CHIP_RV515)) {
+                                        /* allow the user to overrride just in case */
+                                        if (radeon_new_pll == 1)
+                                                pll->algo = PLL_ALGO_NEW;
+                                        else
+                                                pll->algo = PLL_ALGO_LEGACY;
+                                }
                         } else {
                                 if (encoder->encoder_type != DRM_MODE_ENCODER_DAC)
                                         pll->flags |= RADEON_PLL_NO_ODD_POST_DIV;