From 0d9958b18e10d7426d94cc3dd024920a40db3ee2 Mon Sep 17 00:00:00 2001 From: Alex Deucher Date: Wed, 1 Sep 2010 12:03:37 -0400 Subject: [PATCH] drm/radeon/kms: force legacy pll algo for RV515 LVDS There has been periodic evidence that LVDS, on at least some panels, prefers the dividers selected by the legacy pll algo. This patch forces the use of the legacy pll algo on RV515 LVDS panels. The old behavior (new pll algo) can be selected by setting the new_pll module parameter to 1. Signed-off-by: Alex Deucher Cc: stable@kernel.org Signed-off-by: Dave Airlie --- drivers/gpu/drm/radeon/atombios_crtc.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) 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; -- 2.20.1