[RFC PATCH 2/2] vivid: add support for reduced fps in video capture

[Prashant Laddha <prladdha@cisco.com>]

With this patch, vivid capture thread can now generate reduced
fps by factor of 1000 / 1001. This is controlled using a boolean
VIVID_CID_REDUCED_FPS added in vivid control. For reduced fps,
capture time is controlled by scaling down timeperframe_vid_cap
with a factor of 1000 / 1001 if VIVID_CID_REDUCED_FPS is true.

Cc: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Prashant Laddha <prladdha@cisco.com>
---
 drivers/media/platform/vivid/vivid-core.h    |  1 +
 drivers/media/platform/vivid/vivid-ctrls.c   | 15 +++++++++++++++
 drivers/media/platform/vivid/vivid-vid-cap.c |  7 ++++++-
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/media/platform/vivid/vivid-core.h b/drivers/media/platform/vivid/vivid-core.h
index c72349c..4a2c8b7 100644
--- a/drivers/media/platform/vivid/vivid-core.h
+++ b/drivers/media/platform/vivid/vivid-core.h
@@ -263,6 +263,7 @@ struct vivid_dev {
 	bool				vflip;
 	bool				vbi_cap_interlaced;
 	bool				loop_video;
+	bool				reduced_fps;
 
 	/* Framebuffer */
 	unsigned long			video_pbase;
diff --git a/drivers/media/platform/vivid/vivid-ctrls.c b/drivers/media/platform/vivid/vivid-ctrls.c
index 339c8b7..6becdfe 100644
--- a/drivers/media/platform/vivid/vivid-ctrls.c
+++ b/drivers/media/platform/vivid/vivid-ctrls.c
@@ -78,6 +78,7 @@
 #define VIVID_CID_TIME_WRAP		(VIVID_CID_VIVID_BASE + 39)
 #define VIVID_CID_MAX_EDID_BLOCKS	(VIVID_CID_VIVID_BASE + 40)
 #define VIVID_CID_PERCENTAGE_FILL	(VIVID_CID_VIVID_BASE + 41)
+#define VIVID_CID_REDUCED_FPS		(VIVID_CID_VIVID_BASE + 42)
 
 #define VIVID_CID_STD_SIGNAL_MODE	(VIVID_CID_VIVID_BASE + 60)
 #define VIVID_CID_STANDARD		(VIVID_CID_VIVID_BASE + 61)
@@ -422,6 +423,10 @@ static int vivid_vid_cap_s_ctrl(struct v4l2_ctrl *ctrl)
 		dev->sensor_vflip = ctrl->val;
 		tpg_s_vflip(&dev->tpg, dev->sensor_vflip ^ dev->vflip);
 		break;
+	case VIVID_CID_REDUCED_FPS:
+		dev->reduced_fps = ctrl->val;
+		vivid_update_format_cap(dev, true);
+		break;
 	case VIVID_CID_HAS_CROP_CAP:
 		dev->has_crop_cap = ctrl->val;
 		vivid_update_format_cap(dev, true);
@@ -599,6 +604,15 @@ static const struct v4l2_ctrl_config vivid_ctrl_vflip = {
 	.step = 1,
 };
 
+static const struct v4l2_ctrl_config vivid_ctrl_reduced_fps = {
+	.ops = &vivid_vid_cap_ctrl_ops,
+	.id = VIVID_CID_REDUCED_FPS,
+	.name = "Reduced fps",
+	.type = V4L2_CTRL_TYPE_BOOLEAN,
+	.max = 1,
+	.step = 1,
+};
+
 static const struct v4l2_ctrl_config vivid_ctrl_has_crop_cap = {
 	.ops = &vivid_vid_cap_ctrl_ops,
 	.id = VIVID_CID_HAS_CROP_CAP,
@@ -1379,6 +1393,7 @@ int vivid_create_controls(struct vivid_dev *dev, bool show_ccs_cap,
 		v4l2_ctrl_new_custom(hdl_vid_cap, &vivid_ctrl_vflip, NULL);
 		v4l2_ctrl_new_custom(hdl_vid_cap, &vivid_ctrl_insert_sav, NULL);
 		v4l2_ctrl_new_custom(hdl_vid_cap, &vivid_ctrl_insert_eav, NULL);
+		v4l2_ctrl_new_custom(hdl_vid_cap, &vivid_ctrl_reduced_fps, NULL);
 		if (show_ccs_cap) {
 			dev->ctrl_has_crop_cap = v4l2_ctrl_new_custom(hdl_vid_cap,
 				&vivid_ctrl_has_crop_cap, NULL);
diff --git a/drivers/media/platform/vivid/vivid-vid-cap.c b/drivers/media/platform/vivid/vivid-vid-cap.c
index ed0b878..2b26059 100644
--- a/drivers/media/platform/vivid/vivid-vid-cap.c
+++ b/drivers/media/platform/vivid/vivid-vid-cap.c
@@ -401,6 +401,7 @@ void vivid_update_format_cap(struct vivid_dev *dev, bool keep_controls)
 {
 	struct v4l2_bt_timings *bt = &dev->dv_timings_cap.bt;
 	unsigned size;
+	u64 pixelclock;
 
 	switch (dev->input_type[dev->input]) {
 	case WEBCAM:
@@ -430,8 +431,12 @@ void vivid_update_format_cap(struct vivid_dev *dev, bool keep_controls)
 		dev->src_rect.width = bt->width;
 		dev->src_rect.height = bt->height;
 		size = V4L2_DV_BT_FRAME_WIDTH(bt) * V4L2_DV_BT_FRAME_HEIGHT(bt);
+		if (dev->reduced_fps)
+			pixelclock = div_u64((bt->pixelclock * 1000), 1001);
+		else
+			pixelclock = bt->pixelclock;
 		dev->timeperframe_vid_cap = (struct v4l2_fract) {
-			size / 100, (u32)bt->pixelclock / 100
+			size / 100, (u32)pixelclock / 100
 		};
 		if (bt->interlaced)
 			dev->field_cap = V4L2_FIELD_ALTERNATE;
-- 
1.9.1