[media] v4l2-common: add v4l_match_dv_timings

Add the v4l_match_dv_timings function that can be used to compare two
v4l2_dv_timings structs.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/v4l2-core/v4l2-common.c

@@ -597,6 +597,39 @@ int v4l_fill_dv_preset_info(u32 preset, struct v4l2_dv_enum_preset *info)
 }
 EXPORT_SYMBOL_GPL(v4l_fill_dv_preset_info);
 
+/**
+ * v4l_match_dv_timings - check if two timings match
+ * @t1 - compare this v4l2_dv_timings struct...
+ * @t2 - with this struct.
+ * @pclock_delta - the allowed pixelclock deviation.
+ *
+ * Compare t1 with t2 with a given margin of error for the pixelclock.
+ */
+bool v4l_match_dv_timings(const struct v4l2_dv_timings *t1,
+			  const struct v4l2_dv_timings *t2,
+			  unsigned pclock_delta)
+{
+	if (t1->type != t2->type || t1->type != V4L2_DV_BT_656_1120)
+		return false;
+	if (t1->bt.width == t2->bt.width &&
+	    t1->bt.height == t2->bt.height &&
+	    t1->bt.interlaced == t2->bt.interlaced &&
+	    t1->bt.polarities == t2->bt.polarities &&
+	    t1->bt.pixelclock >= t2->bt.pixelclock - pclock_delta &&
+	    t1->bt.pixelclock <= t2->bt.pixelclock + pclock_delta &&
+	    t1->bt.hfrontporch == t2->bt.hfrontporch &&
+	    t1->bt.vfrontporch == t2->bt.vfrontporch &&
+	    t1->bt.vsync == t2->bt.vsync &&
+	    t1->bt.vbackporch == t2->bt.vbackporch &&
+	    (!t1->bt.interlaced ||
+		(t1->bt.il_vfrontporch == t2->bt.il_vfrontporch &&
+		 t1->bt.il_vsync == t2->bt.il_vsync &&
+		 t1->bt.il_vbackporch == t2->bt.il_vbackporch)))
+		return true;
+	return false;
+}
+EXPORT_SYMBOL_GPL(v4l_match_dv_timings);
+
 const struct v4l2_frmsize_discrete *v4l2_find_nearest_format(
 		const struct v4l2_discrete_probe *probe,
 		s32 width, s32 height)

include/media/v4l2-common.h

@@ -212,4 +212,8 @@ const struct v4l2_frmsize_discrete *v4l2_find_nearest_format(
 		const struct v4l2_discrete_probe *probe,
 		s32 width, s32 height);
 
+bool v4l_match_dv_timings(const struct v4l2_dv_timings *t1,
+			  const struct v4l2_dv_timings *t2,
+			  unsigned pclock_delta);
+
 #endif /* V4L2_COMMON_H_ */