media: camss: Take in account sensor skip frames

When streaming is starting ask the sensor for its skip frames value.
Max supported frame skip is 29 frames, so clip it if it is higher.

Signed-off-by: Todor Tomov <todor.tomov@linaro.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/platform/qcom/camss/camss-vfe.c

@@ -37,9 +37,9 @@
 /* VFE halt timeout */
 #define VFE_HALT_TIMEOUT_MS 100
 /* Max number of frame drop updates per frame */
-#define VFE_FRAME_DROP_UPDATES 5
-/* Frame drop value. NOTE: VAL + UPDATES should not exceed 31 */
-#define VFE_FRAME_DROP_VAL 20
+#define VFE_FRAME_DROP_UPDATES 2
+/* Frame drop value. VAL + UPDATES - 1 should not exceed 31 */
+#define VFE_FRAME_DROP_VAL 30
 
 #define VFE_NEXT_SOF_MS 500
 
@@ -659,14 +659,27 @@ static int vfe_enable_output(struct vfe_line *line)
 	struct vfe_device *vfe = to_vfe(line);
 	struct vfe_output *output = &line->output;
 	const struct vfe_hw_ops *ops = vfe->ops;
+	struct media_entity *sensor;
 	unsigned long flags;
+	unsigned int frame_skip = 0;
 	unsigned int i;
 	u16 ub_size;
 
 	ub_size = ops->get_ub_size(vfe->id);
 	if (!ub_size)
 		return -EINVAL;
 
+	sensor = camss_find_sensor(&line->subdev.entity);
+	if (sensor) {
+		struct v4l2_subdev *subdev =
+					media_entity_to_v4l2_subdev(sensor);
+
+		v4l2_subdev_call(subdev, sensor, g_skip_frames, &frame_skip);
+		/* Max frame skip is 29 frames */
+		if (frame_skip > VFE_FRAME_DROP_VAL - 1)
+			frame_skip = VFE_FRAME_DROP_VAL - 1;
+	}
+
 	spin_lock_irqsave(&vfe->output_lock, flags);
 
 	ops->reg_update_clear(vfe, line->id);
@@ -695,10 +708,10 @@ static int vfe_enable_output(struct vfe_line *line)
 
 	switch (output->state) {
 	case VFE_OUTPUT_SINGLE:
-		vfe_output_frame_drop(vfe, output, 1);
+		vfe_output_frame_drop(vfe, output, 1 << frame_skip);
 		break;
 	case VFE_OUTPUT_CONTINUOUS:
-		vfe_output_frame_drop(vfe, output, 3);
+		vfe_output_frame_drop(vfe, output, 3 << frame_skip);
 		break;
 	default:
 		vfe_output_frame_drop(vfe, output, 0);

drivers/media/platform/qcom/camss/camss.c

@@ -346,7 +346,7 @@ void camss_disable_clocks(int nclocks, struct camss_clock *clock)
  *
  * Return a pointer to sensor media entity or NULL if not found
  */
-static struct media_entity *camss_find_sensor(struct media_entity *entity)
+struct media_entity *camss_find_sensor(struct media_entity *entity)
 {
 	struct media_pad *pad;
 

drivers/media/platform/qcom/camss/camss.h

@@ -106,6 +106,7 @@ void camss_add_clock_margin(u64 *rate);
 int camss_enable_clocks(int nclocks, struct camss_clock *clock,
 			struct device *dev);
 void camss_disable_clocks(int nclocks, struct camss_clock *clock);
+struct media_entity *camss_find_sensor(struct media_entity *entity);
 int camss_get_pixel_clock(struct media_entity *entity, u32 *pixel_clock);
 int camss_pm_domain_on(struct camss *camss, int id);
 void camss_pm_domain_off(struct camss *camss, int id);