[Intel-gfx] [PATCH v2 02/13] drm/i915/dp: return errors from rate_to_index()

[Jani Nikula]

We shouldn't silently use the first element if we can't find the rate
we're looking for. Make rate_to_index() more generally useful, and
fallback to the first element in the caller, with a big warning.

Cc: Manasi Navare <manasi.d.navare at intel.com>
Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula at intel.com>
---
 drivers/gpu/drm/i915/intel_dp.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 3b809b6d186d..75926a5b900f 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -1548,9 +1548,9 @@ static int rate_to_index(const int *rates, int len, int rate)
 
 	for (i = 0; i < len; i++)
 		if (rate == rates[i])
-			break;
+			return i;
 
-	return i;
+	return -1;
 }
 
 int
@@ -1568,8 +1568,13 @@ intel_dp_max_link_rate(struct intel_dp *intel_dp)
 
 int intel_dp_rate_select(struct intel_dp *intel_dp, int rate)
 {
-	return rate_to_index(intel_dp->sink_rates, intel_dp->num_sink_rates,
-			     rate);
+	int i = rate_to_index(intel_dp->sink_rates, intel_dp->num_sink_rates,
+			      rate);
+
+	if (WARN_ON(i < 0))
+		i = 0;
+
+	return i;
 }
 
 void intel_dp_compute_rate(struct intel_dp *intel_dp, int port_clock,
-- 
2.1.4