drm/i915: Use DIV_ROUND_UP() when calculating number of required FDI lanes

If we need precisely N lanes to satisfy the FDI bandwidth requirement,
the code would still claim that we need N+1 lanes. Use DIV_ROUND_UP()
to get a more accurate answer.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
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 45bd176..227f660 100644 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -6161,7 +6161,7 @@ int ironlake_get_lanes_required(int target_clock, int link_bw, int bpp)
         * is 2.5%; use 5% for safety's sake.
         */
        u32 bps = target_clock * bpp * 21 / 20;
-       return bps / (link_bw * 8) + 1;
+       return DIV_ROUND_UP(bps, link_bw * 8);
 }
 
 static bool ironlake_needs_fb_cb_tune(struct dpll *dpll, int factor)