media: ov6650: Fix missing frame interval enumeration support

According to v4l2-compliance utility, a video device which supports
V4L2_CAP_TIMEPERFRAME via .vidioc_s_parm() operation should also
support .vidioc_enum_frameintervals().  If the former is implemented
via a call to v4l2_s_parm_cap() which in turn calls a subdevice
.s_frame_interval() pad operation, the video device may want to
implement the latter by passing frame interval enumeration requests to
the subdevice .enum_frame_intervals() video operation.  If that
operation is not supported by the subdevice and failure is returned by
the video device, the compliance test issues a warning.

Implement the missing pad operation.  Enumerate frame intervals
possible to be set via pixel clock adjustment, as implemented by
.s_frame_interval(), but not exceeding a reasonable maximum of 1
second.

[Sakari Ailus: Rebased on mbus config pad op patches]
Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

drivers/media/i2c/ov6650.c

@@ -764,6 +764,33 @@ static int ov6650_enum_mbus_code(struct v4l2_subdev *sd,
 	return 0;
 }
 
+static int ov6650_enum_frame_interval(struct v4l2_subdev *sd,
+				    struct v4l2_subdev_state *sd_state,
+				    struct v4l2_subdev_frame_interval_enum *fie)
+{
+	int i;
+
+	/* enumerate supported frame intervals not exceeding 1 second */
+	if (fie->index > CLKRC_DIV_MASK ||
+	    GET_CLKRC_DIV(fie->index) > FRAME_RATE_MAX)
+		return -EINVAL;
+
+	for (i = 0; i < ARRAY_SIZE(ov6650_codes); i++)
+		if (fie->code == ov6650_codes[i])
+			break;
+	if (i == ARRAY_SIZE(ov6650_codes))
+		return -EINVAL;
+
+	if (!fie->width || fie->width > W_CIF ||
+	    !fie->height || fie->height > H_CIF)
+		return -EINVAL;
+
+	fie->interval.numerator = GET_CLKRC_DIV(fie->index);
+	fie->interval.denominator = FRAME_RATE_MAX;
+
+	return 0;
+}
+
 static int ov6650_g_frame_interval(struct v4l2_subdev *sd,
 				   struct v4l2_subdev_frame_interval *ival)
 {
@@ -977,6 +1004,7 @@ static const struct v4l2_subdev_video_ops ov6650_video_ops = {
 
 static const struct v4l2_subdev_pad_ops ov6650_pad_ops = {
 	.enum_mbus_code		= ov6650_enum_mbus_code,
+	.enum_frame_interval	= ov6650_enum_frame_interval,
 	.get_selection		= ov6650_get_selection,
 	.set_selection		= ov6650_set_selection,
 	.get_fmt		= ov6650_get_fmt,