drm/i915: Factor in pixel-repeat in FDI M/N calculation

Fixes the modesetting on the secondary panel of the Libretto W100 and
presumably many more Ironlake laptops with SDVO LVDS displays.

Reported-and-tested-by: Matthew Willoughby <mattfredwill@gmail.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: stable@kernel.org

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index fac118b2df7..d9b7092439e 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3710,6 +3710,7 @@ static int intel_crtc_mode_set(struct drm_crtc *crtc,
 
         /* FDI link */
         if (HAS_PCH_SPLIT(dev)) {
+                int pixel_multiplier = intel_mode_get_pixel_multiplier(adjusted_mode);
                 int lane = 0, link_bw, bpp;
                 /* CPU eDP doesn't require FDI link, so just set DP M/N
                    according to current link config */
@@ -3793,6 +3794,8 @@ static int intel_crtc_mode_set(struct drm_crtc *crtc,
 
                 intel_crtc->fdi_lanes = lane;
 
+                if (pixel_multiplier > 1)
+                        link_bw *= pixel_multiplier;
                 ironlake_compute_m_n(bpp, lane, target_clock, link_bw, &m_n);
         }