drm/i915: Fix VLV PLL LPF coefficients for DAC

The current PLL settings produce a rather unstable picture when
I hook up a VLV to my HP ZR24w display via a VGA cable.

According to VLV2A0_DP_eDP_HDMI_DPIO_driver_vbios_notes_9, we should
use the the same LPF coefficients for DAC as we do for HDMI and RBR DP.
And indeed that seems to cure the shivers.

v2: Add the name of the relevant document to the commit message

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index d723819..749d428 100644 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -4404,6 +4404,7 @@ static void vlv_update_pll(struct intel_crtc *crtc)
 
        /* Set HBR and RBR LPF coefficients */
        if (crtc->config.port_clock == 162000 ||
+           intel_pipe_has_type(&crtc->base, INTEL_OUTPUT_ANALOG) ||
            intel_pipe_has_type(&crtc->base, INTEL_OUTPUT_HDMI))
                vlv_dpio_write(dev_priv, DPIO_LFP_COEFF(pipe),
                                 0x005f0021);