ivtv: attach yuv field order to each frame

From: Ian Armstrong <ian@iarmst.demon.co.uk>

In the current driver, the field order is global. As soon as it's changed it
takes immediate effect. This is a problem when the video changes order mid
stream. Although it mostly works okay, the video may judder / flicker.

This patch attaches the field order to the frame, so that any buffered frames
will not be displayed until the correct field. In the event that the field
order is changed mid stream, the driver will ensure that the previous frame
is displayed for a minimum of 3 fields. These are the two original fields the
frame should have occupied, plus the one extra since the new frame still has
to wait for the correct field.

Signed-off-by: Ian Armstrong <ian@iarmst.demon.co.uk>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>

3 files changed, 31 insertions, 10 deletions

diff --git a/linux/drivers/media/video/ivtv/ivtv-driver.h b/linux/drivers/media/video/ivtv/ivtv-driver.h
index f4fe889d9..a6a52bae7 100644
--- a/linux/drivers/media/video/ivtv/ivtv-driver.h
+++ b/linux/drivers/media/video/ivtv/ivtv-driver.h
@@ -538,6 +538,7 @@ struct yuv_frame_info
 	u32 tru_w;
 	u32 tru_h;
 	u32 offset_y;
+	int lace_mode;
 };
 
 #define IVTV_YUV_MODE_INTERLACED	0x00
@@ -610,7 +611,6 @@ struct yuv_playback_info
 	int decode_height;
 
 	int frame_interlaced;
-	int frame_interlaced_last;
 
 	int lace_mode;
 	int lace_threshold;
@@ -621,6 +621,11 @@ struct yuv_playback_info
 
 	u32 yuv_forced_update;
 	int update_frame;
+
+	int sync_field[4];  /* Field to sync on */
+	int field_delay[4]; /* Flag to extend duration of previous frame */
+	u8 fields_lapsed;   /* Counter used when delaying a frame */
+
 	struct yuv_frame_info new_frame_info[4];
 	struct yuv_frame_info old_frame_info;
 	struct yuv_frame_info old_frame_info_args;
diff --git a/linux/drivers/media/video/ivtv/ivtv-irq.c b/linux/drivers/media/video/ivtv/ivtv-irq.c
index 405f7e4b7..65622c1e4 100644
--- a/linux/drivers/media/video/ivtv/ivtv-irq.c
+++ b/linux/drivers/media/video/ivtv/ivtv-irq.c
@@ -704,17 +704,21 @@ static void ivtv_irq_vsync(struct ivtv *itv)
 
 	if (0) IVTV_DEBUG_IRQ("DEC VSYNC\n");
 
-	if (((frame ^ itv->yuv_info.lace_sync_field) == 0 && ((itv->lastVsyncFrame & 1) ^ itv->yuv_info.lace_sync_field)) ||
+	if (((frame ^ itv->yuv_info.sync_field[last_dma_frame]) == 0 &&
+		((itv->lastVsyncFrame & 1) ^ itv->yuv_info.sync_field[last_dma_frame])) ||
 			(frame != (itv->lastVsyncFrame & 1) && !itv->yuv_info.frame_interlaced)) {
 		int next_dma_frame = last_dma_frame;
 
-		if (next_dma_frame >= 0 && next_dma_frame != atomic_read(&itv->yuv_info.next_fill_frame)) {
-			write_reg(yuv_offset[next_dma_frame] >> 4, 0x82c);
-			write_reg((yuv_offset[next_dma_frame] + IVTV_YUV_BUFFER_UV_OFFSET) >> 4, 0x830);
-			write_reg(yuv_offset[next_dma_frame] >> 4, 0x834);
-			write_reg((yuv_offset[next_dma_frame] + IVTV_YUV_BUFFER_UV_OFFSET) >> 4, 0x838);
-			next_dma_frame = (next_dma_frame + 1) & 0x3;
-			atomic_set(&itv->yuv_info.next_dma_frame, next_dma_frame);
+		if (!(itv->yuv_info.frame_interlaced && itv->yuv_info.field_delay[next_dma_frame] && itv->yuv_info.fields_lapsed < 1)) {
+			if (next_dma_frame >= 0 && next_dma_frame != atomic_read(&itv->yuv_info.next_fill_frame)) {
+				write_reg(yuv_offset[next_dma_frame] >> 4, 0x82c);
+				write_reg((yuv_offset[next_dma_frame] + IVTV_YUV_BUFFER_UV_OFFSET) >> 4, 0x830);
+				write_reg(yuv_offset[next_dma_frame] >> 4, 0x834);
+				write_reg((yuv_offset[next_dma_frame] + IVTV_YUV_BUFFER_UV_OFFSET) >> 4, 0x838);
+				next_dma_frame = (next_dma_frame + 1) & 0x3;
+				atomic_set(&itv->yuv_info.next_dma_frame, next_dma_frame);
+				itv->yuv_info.fields_lapsed = -1;
+			}
 		}
 	}
 	if (frame != (itv->lastVsyncFrame & 1)) {
@@ -755,6 +759,8 @@ static void ivtv_irq_vsync(struct ivtv *itv)
 				set_bit(IVTV_F_I_HAVE_WORK, &itv->i_flags);
 			}
 		}
+
+		itv->yuv_info.fields_lapsed ++;
 	}
 }
 
diff --git a/linux/drivers/media/video/ivtv/ivtv-yuv.c b/linux/drivers/media/video/ivtv/ivtv-yuv.c
index 5c94d3282..fa8c76f3d 100644
--- a/linux/drivers/media/video/ivtv/ivtv-yuv.c
+++ b/linux/drivers/media/video/ivtv/ivtv-yuv.c
@@ -612,7 +612,6 @@ static void ivtv_yuv_handle_vertical(struct ivtv *itv, struct yuv_frame_info *wi
 		itv->yuv_info.v_filter_2 = v_filter_2;
 	}
 
-	itv->yuv_info.frame_interlaced_last = itv->yuv_info.frame_interlaced;
 }
 
 /* Modify the supplied coordinate information to fit the visible osd area */
@@ -799,6 +798,7 @@ static u32 ivtv_yuv_window_setup (struct ivtv *itv, struct yuv_frame_info *windo
 	    (itv->yuv_info.old_frame_info.src_y != window->src_y) ||
 	    (itv->yuv_info.old_frame_info.pan_y != window->pan_y) ||
 	    (itv->yuv_info.old_frame_info.vis_h != window->vis_h) ||
+	    (itv->yuv_info.old_frame_info.lace_mode != window->lace_mode) ||
 	    (itv->yuv_info.old_frame_info.interlaced_y != window->interlaced_y) ||
 	    (itv->yuv_info.old_frame_info.interlaced_uv != window->interlaced_uv)) {
 		yuv_update |= IVTV_YUV_UPDATE_VERTICAL;
@@ -970,6 +970,9 @@ int ivtv_yuv_prep_frame(struct ivtv *itv, struct ivtv_dma_frame *args)
 	itv->yuv_info.new_frame_info[frame].tru_w = args->src_width;
 	itv->yuv_info.new_frame_info[frame].tru_h = args->src_height;
 
+	/* Snapshot field order */
+	itv->yuv_info.sync_field[frame] = itv->yuv_info.lace_sync_field;
+
 	/* Are we going to offset the Y plane */
 	if (args->src.height + args->src.top < 512-16)
 		itv->yuv_info.new_frame_info[frame].offset_y = 1;
@@ -985,6 +988,7 @@ int ivtv_yuv_prep_frame(struct ivtv *itv, struct ivtv_dma_frame *args)
 	itv->yuv_info.new_frame_info[frame].update = 0;
 	itv->yuv_info.new_frame_info[frame].interlaced_y = 0;
 	itv->yuv_info.new_frame_info[frame].interlaced_uv = 0;
+	itv->yuv_info.new_frame_info[frame].lace_mode = itv->yuv_info.lace_mode;
 
 	if (memcmp (&itv->yuv_info.old_frame_info_args, &itv->yuv_info.new_frame_info[frame],
 	    sizeof (itv->yuv_info.new_frame_info[frame]))) {
@@ -995,6 +999,12 @@ int ivtv_yuv_prep_frame(struct ivtv *itv, struct ivtv_dma_frame *args)
 
 	itv->yuv_info.new_frame_info[frame].update |= register_update;
 
+	/* Should this frame be delayed ? */
+	if (itv->yuv_info.sync_field[frame] != itv->yuv_info.sync_field[(frame - 1) & 3])
+		itv->yuv_info.field_delay[frame] = 1;
+	else
+		itv->yuv_info.field_delay[frame] = 0;
+
 	/* DMA the frame */
 	mutex_lock(&itv->udma.lock);