drm/i915: reverse dp link param selection, prefer fast over wide again

... it's this time of the year again. Originally we've frobbed this to
fix up some regressions, but maybe our DP code improved sufficiently
now that we can dare to do again what the spec recommends.

This reverts

commit 2514bc510d0c3aadcc5204056bb440fa36845147
Author: Jesse Barnes <jbarnes@virtuousgeek.org>
Date:   Thu Jun 21 15:13:50 2012 -0700

    drm/i915: prefer wide & slow to fast & narrow in DP configs

I'm pretty sure I'll regret this patch, but otoh I expect we won't
make progress here without poking the devil occasionally.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=73694
Cc: peter@colberg.org
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Tested-by: Itai BEN YAACOV <candeb@free.fr>
Tested-by: David En <d.engraf@arcor.de>
Reported-and-Tested-by: Marcus Bergner <marcusbergner@gmail.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 10154ec77b984fdd65289fca01d328116d3f2d3d..62e8efedce52c6efc09b606cbc2defabfbc8c208 100644 (file)
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -909,8 +909,8 @@ intel_dp_compute_config(struct intel_encoder *encoder,
                mode_rate = intel_dp_link_required(adjusted_mode->crtc_clock,
                                                   bpp);
 
-               for (clock = 0; clock <= max_clock; clock++) {
-                       for (lane_count = 1; lane_count <= max_lane_count; lane_count <<= 1) {
+               for (lane_count = 1; lane_count <= max_lane_count; lane_count <<= 1) {
+                       for (clock = 0; clock <= max_clock; clock++) {
                                link_clock = drm_dp_bw_code_to_link_rate(bws[clock]);
                                link_avail = intel_dp_max_data_rate(link_clock,
                                                                    lane_count);