From fdb14d335f8c3724fcc5f4db8e1a8fe634ca0afc Mon Sep 17 00:00:00 2001 From: Manasi Navare Date: Thu, 8 Dec 2016 19:05:12 -0800 Subject: [PATCH] drm/i915: Find fallback link rate/lane count If link training fails, then we need to fallback to lower link rate first and if link training fails at RBR, then fallback to lower lane count. This function finds the next lower link rate/lane count value after link training failure and limits the max link_rate and lane_count values to these fallback values. v7: * Remove unnecessary intializations and remove redundant call to intel_dp_common_rates (Jani Nikula) v6: * Cap the max link rate and lane count to the max values obtained during fallback link training (Daniel Vetter) v5: * Start the fallback at the lane count value passed not the max lane count (Jani Nikula) v4: * Remove the redundant variable link_train_failed v3: * Remove fallback_link_rate_index variable, just obtain that using the helper intel_dp_link_rate_index (Jani Nikula) v2: Squash the patch that returns the link rate index (Jani Nikula) Acked-by: Tony Cheng Acked-by: Harry Wentland Cc: Ville Syrjala Cc: Jani Nikula Cc: Daniel Vetter Signed-off-by: Manasi Navare Reviewed-by: Jani Nikula Signed-off-by: Jani Nikula Link: http://patchwork.freedesktop.org/patch/msgid/1481252712-12925-1-git-send-email-manasi.d.navare@intel.com --- drivers/gpu/drm/i915/intel_dp.c | 38 ++++++++++++++++++++++++++++++++ drivers/gpu/drm/i915/intel_drv.h | 2 ++ 2 files changed, 40 insertions(+) diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index 434dc7d4773a..1b5e0d0c315f 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -278,6 +278,44 @@ static int intel_dp_common_rates(struct intel_dp *intel_dp, common_rates); } +static int intel_dp_link_rate_index(struct intel_dp *intel_dp, + int *common_rates, int link_rate) +{ + int common_len; + int index; + + common_len = intel_dp_common_rates(intel_dp, common_rates); + for (index = 0; index < common_len; index++) { + if (link_rate == common_rates[common_len - index - 1]) + return common_len - index - 1; + } + + return -1; +} + +int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp, + int link_rate, uint8_t lane_count) +{ + int common_rates[DP_MAX_SUPPORTED_RATES]; + int link_rate_index; + + link_rate_index = intel_dp_link_rate_index(intel_dp, + common_rates, + link_rate); + if (link_rate_index > 0) { + intel_dp->max_sink_link_bw = drm_dp_link_rate_to_bw_code(common_rates[link_rate_index - 1]); + intel_dp->max_sink_lane_count = lane_count; + } else if (lane_count > 1) { + intel_dp->max_sink_link_bw = intel_dp_max_link_bw(intel_dp); + intel_dp->max_sink_lane_count = lane_count >> 1; + } else { + DRM_ERROR("Link Training Unsuccessful\n"); + return -1; + } + + return 0; +} + static enum drm_mode_status intel_dp_mode_valid(struct drm_connector *connector, struct drm_display_mode *mode) diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h index 8e5f2a1e75d8..ac70052a9a61 100644 --- a/drivers/gpu/drm/i915/intel_drv.h +++ b/drivers/gpu/drm/i915/intel_drv.h @@ -1400,6 +1400,8 @@ bool intel_dp_init_connector(struct intel_digital_port *intel_dig_port, void intel_dp_set_link_params(struct intel_dp *intel_dp, int link_rate, uint8_t lane_count, bool link_mst); +int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp, + int link_rate, uint8_t lane_count); void intel_dp_start_link_train(struct intel_dp *intel_dp); void intel_dp_stop_link_train(struct intel_dp *intel_dp); void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode); -- 2.20.1