From 9dbf5a4efd8afa2b831b0f76b4f9cab9480af817 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= Date: Wed, 3 Oct 2018 21:42:10 +0300 Subject: [PATCH] drm/i915: Provide more clues as to why MST is/is not used MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Always print out the information whether the port and sink can each do MST. And let's include the modparam in the debug output as well. Makes life a little less confusing when you don't have to wonder why MST isn't kicking in. This does cause a slight change in our behaviour towards the sink. Previously we only read the MSTM_CAP register after passing all the other checks. Now we will read that register regardless. Hopefully some crazy sink doesn't get confused by a simple register read. Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20181003184210.1306-1-ville.syrjala@linux.intel.com Reviewed-by: Dhinakaran Pandiyan --- drivers/gpu/drm/i915/intel_dp.c | 33 ++++++++++++++++++--------------- 1 file changed, 18 insertions(+), 15 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index 15a981ef5966..1a510cf58fb5 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -4050,16 +4050,10 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp) } static bool -intel_dp_can_mst(struct intel_dp *intel_dp) +intel_dp_sink_can_mst(struct intel_dp *intel_dp) { u8 mstm_cap; - if (!i915_modparams.enable_dp_mst) - return false; - - if (!intel_dp->can_mst) - return false; - if (intel_dp->dpcd[DP_DPCD_REV] < 0x12) return false; @@ -4069,21 +4063,30 @@ intel_dp_can_mst(struct intel_dp *intel_dp) return mstm_cap & DP_MST_CAP; } +static bool +intel_dp_can_mst(struct intel_dp *intel_dp) +{ + return i915_modparams.enable_dp_mst && + intel_dp->can_mst && + intel_dp_sink_can_mst(intel_dp); +} + static void intel_dp_configure_mst(struct intel_dp *intel_dp) { - if (!i915_modparams.enable_dp_mst) - return; + struct intel_encoder *encoder = + &dp_to_dig_port(intel_dp)->base; + bool sink_can_mst = intel_dp_sink_can_mst(intel_dp); + + DRM_DEBUG_KMS("MST support? port %c: %s, sink: %s, modparam: %s\n", + port_name(encoder->port), yesno(intel_dp->can_mst), + yesno(sink_can_mst), yesno(i915_modparams.enable_dp_mst)); if (!intel_dp->can_mst) return; - intel_dp->is_mst = intel_dp_can_mst(intel_dp); - - if (intel_dp->is_mst) - DRM_DEBUG_KMS("Sink is MST capable\n"); - else - DRM_DEBUG_KMS("Sink is not MST capable\n"); + intel_dp->is_mst = sink_can_mst && + i915_modparams.enable_dp_mst; drm_dp_mst_topology_mgr_set_mst(&intel_dp->mst_mgr, intel_dp->is_mst);