drm/i915/dp: abstract training pattern selection

Make it cleaner to add more checks in the function. No functional
changes.

Cc: Ander Conselvan de Oliveira <conselvan2@gmail.com>
Cc: Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>
Reviewed-by: Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>
Cc: drm-intel-fixes@lists.freedesktop.org # dependency on the next patch
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1454667370-8001-1-git-send-email-jani.nikula@intel.com
(cherry picked from commit 23a5110dc619073b57d90c36eae383f51df03aac)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

diff --git a/drivers/gpu/drm/i915/intel_dp_link_training.c b/drivers/gpu/drm/i915/intel_dp_link_training.c
index 88887938e0bfd3e0cf3e7bdebd66a145f7e036a7..83e667b92fda827e592ccd6a478065d7fbe31d2a 100644 (file)
--- a/drivers/gpu/drm/i915/intel_dp_link_training.c
+++ b/drivers/gpu/drm/i915/intel_dp_link_training.c
@@ -215,16 +215,15 @@ intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp)
        }
 }
 
-static void
-intel_dp_link_training_channel_equalization(struct intel_dp *intel_dp)
+/*
+ * Pick training pattern for channel equalization. Training Pattern 3 for HBR2
+ * or 1.2 devices that support it, Training Pattern 2 otherwise.
+ */
+static u32 intel_dp_training_pattern(struct intel_dp *intel_dp)
 {
-       bool channel_eq = false;
-       int tries, cr_tries;
-       uint32_t training_pattern = DP_TRAINING_PATTERN_2;
+       u32 training_pattern = DP_TRAINING_PATTERN_2;
 
        /*
-        * Training Pattern 3 for HBR2 or 1.2 devices that support it.
-        *
         * Intel platforms that support HBR2 also support TPS3. TPS3 support is
         * also mandatory for downstream devices that support HBR2.
         *
@@ -237,6 +236,18 @@ intel_dp_link_training_channel_equalization(struct intel_dp *intel_dp)
        else if (intel_dp->link_rate == 540000)
                DRM_ERROR("5.4 Gbps link rate without HBR2/TPS3 support\n");
 
+       return training_pattern;
+}
+
+static void
+intel_dp_link_training_channel_equalization(struct intel_dp *intel_dp)
+{
+       bool channel_eq = false;
+       int tries, cr_tries;
+       u32 training_pattern;
+
+       training_pattern = intel_dp_training_pattern(intel_dp);
+
        /* channel equalization */
        if (!intel_dp_set_link_train(intel_dp,
                                     training_pattern |