Pretty useful to debug our DP bandwidth woes. v2: Also print out the required and available link bandwidth, suggested by Chris Wilson. v3: Also print out the input parameters so that diagnosing failures to find a valid dp link configuration is possible. v4: s/Display port/DP/ to shorten the output. Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk> Signed-Off-by: Daniel Vetter <daniel.vetter at ffwll.ch> --- drivers/gpu/drm/i915/intel_dp.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index 44cf32c..4b7a286 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -688,7 +688,7 @@ intel_dp_mode_fixup(struct drm_encoder *encoder, struct drm_display_mode *mode, int lane_count, clock; int max_lane_count = intel_dp_max_lane_count(intel_dp); int max_clock = intel_dp_max_link_bw(intel_dp) == DP_LINK_BW_2_7 ? 1 : 0; - int bpp; + int bpp, mode_rate; static int bws[2] = { DP_LINK_BW_1_62, DP_LINK_BW_2_7 }; if (is_edp(intel_dp) && intel_dp->panel_fixed_mode) { @@ -702,24 +702,30 @@ intel_dp_mode_fixup(struct drm_encoder *encoder, struct drm_display_mode *mode, mode->clock = intel_dp->panel_fixed_mode->clock; } + DRM_DEBUG_KMS("Display port link computation with max lane count %i " + "max bw %02x pixel clock %iKHz\n", + max_lane_count, bws[max_clock], mode->clock); + if (!intel_dp_adjust_dithering(intel_dp, mode, adjusted_mode)) return false; bpp = adjusted_mode->private_flags & INTEL_MODE_DP_FORCE_6BPC ? 18 : 24; + mode_rate = intel_dp_link_required(mode->clock, bpp); for (lane_count = 1; lane_count <= max_lane_count; lane_count <<= 1) { for (clock = 0; clock <= max_clock; clock++) { int link_avail = intel_dp_max_data_rate(intel_dp_link_clock(bws[clock]), lane_count); - if (intel_dp_link_required(mode->clock, bpp) - <= link_avail) { + if (mode_rate <= link_avail) { intel_dp->link_bw = bws[clock]; intel_dp->lane_count = lane_count; adjusted_mode->clock = intel_dp_link_clock(intel_dp->link_bw); DRM_DEBUG_KMS("Display port link bw %02x lane " - "count %d clock %d\n", + "count %d clock %d bpp %d\n", intel_dp->link_bw, intel_dp->lane_count, - adjusted_mode->clock); + adjusted_mode->clock, bpp); + DRM_DEBUG_KMS("Display port link bw required %i available %i\n", + mode_rate, link_avail); return true; } } -- 1.7.10