[Intel-gfx] [PATCH] drm/i915: optimzie eDP 1.4 config

[Lee, Shawn C]

eDP 1.4 introduce a new link rates flexibility and selection.
It provided system specific link rate optimization and power
efficiency. We should keep eDP 1.3 and older version to use
max link rate approach to avoid any side effect. And eDP 1.4
used the optimization link rate and lane count setting.

Cc: Matt Atwood <matthew.s.atwood at intel.com>
Signed-off-by: Lee, Shawn C <shawn.c.lee at intel.com>
---
 drivers/gpu/drm/i915/intel_dp.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 436c22de33b6..903d640fe712 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -1953,8 +1953,10 @@ intel_dp_compute_link_config(struct intel_encoder *encoder,
 		 * configuration, and typically these values correspond to the
 		 * native resolution of the panel.
 		 */
-		limits.min_lane_count = limits.max_lane_count;
-		limits.min_clock = limits.max_clock;
+		if (intel_dp->edp_dpcd[0] <= DP_EDP_13) {
+			limits.min_lane_count = limits.max_lane_count;
+			limits.min_clock = limits.max_clock;
+		}
 	}
 
 	intel_dp_adjust_compliance_config(intel_dp, pipe_config, &limits);
-- 
2.7.4