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;