[Intel-gfx] [PATCH] drm/i915/dp: Add a helper function to return DP link rate index

[Manasi Navare]

Common rates array is used to keep track of common rates
supported between DP sink and source. This helper function
returns the index of a specific link rate in this common rates
array.

This is in prep with patches for DP Link training compliance
tests that need an index for the link rate specified by the
test as well as for link training failure handling patches that
require index of fallback link rate.

Cc: Jani Nikula <jani.nikula at linux.intel.com>
Cc: Daniel Vetter <daniel.vetter at intel.com>
Cc: Ville Syrjala <ville.syrjala at linux.intel.com>
Signed-off-by: Manasi Navare <manasi.d.navare at intel.com>
---
 drivers/gpu/drm/i915/intel_dp.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 90283ed..bf72335 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -288,6 +288,21 @@ 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;
+}
+
 static enum drm_mode_status
 intel_dp_mode_valid(struct drm_connector *connector,
 		    struct drm_display_mode *mode)
-- 
1.9.1