V4L/DVB (6095): ivtv: fix VIDIOC_G_ENC_INDEX flag handling

Due to a documentation bug (the type mask is 3 bits long, not 2) the wrong
frame types were filled in: the B and P frame types were swapped.

This bug also hid a second bug: when a capture is stopped a last entry is
written into the pgm index buffer with internal type 0, denoting the end
of the program. This entry wasn't ignored, instead it was accidentally
returned to the caller as a P frame.
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

Documentation/video4linux/cx2341x/fw-encoder-api.txt

@@ -407,8 +407,10 @@ Description
 		u32 length;		// Length of this frame
 		u32 offset_low;		// Offset in the file of the
 		u32 offset_high;	// start of this frame
-		u32 mask1;		// Bits 0-1 are the type mask:
+		u32 mask1;		// Bits 0-2 are the type mask:
 					// 1=I, 2=P, 4=B
+					// 0=End of Program Index, other fields
+					//   are invalid.
 		u32 pts;		// The PTS of the frame
 		u32 mask2;		// Bit 0 is bit 32 of the pts.
 	};

drivers/media/video/ivtv/ivtv-fileops.c

@@ -190,7 +190,9 @@ static void ivtv_update_pgm_info(struct ivtv *itv)
 		int idx = (itv->pgm_info_write_idx + i) % itv->pgm_info_num;
 		struct v4l2_enc_idx_entry *e = itv->pgm_info + idx;
 		u32 addr = itv->pgm_info_offset + 4 + idx * 24;
-		const int mapping[] = { V4L2_ENC_IDX_FRAME_P, V4L2_ENC_IDX_FRAME_I, V4L2_ENC_IDX_FRAME_B, 0 };
+		const int mapping[8] = { -1, V4L2_ENC_IDX_FRAME_I, V4L2_ENC_IDX_FRAME_P, -1,
+			V4L2_ENC_IDX_FRAME_B, -1, -1, -1 };
+					// 1=I, 2=P, 4=B
 
 		e->offset = read_enc(addr + 4) + ((u64)read_enc(addr + 8) << 32);
 		if (e->offset > itv->mpg_data_received) {
@@ -199,7 +201,7 @@ static void ivtv_update_pgm_info(struct ivtv *itv)
 		e->offset += itv->vbi_data_inserted;
 		e->length = read_enc(addr);
 		e->pts = read_enc(addr + 16) + ((u64)(read_enc(addr + 20) & 1) << 32);
-		e->flags = mapping[read_enc(addr + 12) & 3];
+		e->flags = mapping[read_enc(addr + 12) & 7];
 		i++;
 	}
 	itv->pgm_info_write_idx = (itv->pgm_info_write_idx + i) % itv->pgm_info_num;

drivers/media/video/ivtv/ivtv-ioctl.c

@@ -1099,14 +1099,21 @@ int ivtv_v4l2_ioctls(struct ivtv *itv, struct file *filp, unsigned int cmd, void
 
 	case VIDIOC_G_ENC_INDEX: {
 		struct v4l2_enc_idx *idx = arg;
+		struct v4l2_enc_idx_entry *e = idx->entry;
+		int entries;
 		int i;
 
-		idx->entries = (itv->pgm_info_write_idx + IVTV_MAX_PGM_INDEX - itv->pgm_info_read_idx) %
+		entries = (itv->pgm_info_write_idx + IVTV_MAX_PGM_INDEX - itv->pgm_info_read_idx) %
 					IVTV_MAX_PGM_INDEX;
-		if (idx->entries > V4L2_ENC_IDX_ENTRIES)
-			idx->entries = V4L2_ENC_IDX_ENTRIES;
-		for (i = 0; i < idx->entries; i++) {
-			idx->entry[i] = itv->pgm_info[(itv->pgm_info_read_idx + i) % IVTV_MAX_PGM_INDEX];
+		if (entries > V4L2_ENC_IDX_ENTRIES)
+			entries = V4L2_ENC_IDX_ENTRIES;
+		idx->entries = 0;
+		for (i = 0; i < entries; i++) {
+			*e = itv->pgm_info[(itv->pgm_info_read_idx + i) % IVTV_MAX_PGM_INDEX];
+			if ((e->flags & V4L2_ENC_IDX_FRAME_MASK) <= V4L2_ENC_IDX_FRAME_B) {
+				idx->entries++;
+				e++;
+			}
 		}
 		itv->pgm_info_read_idx = (itv->pgm_info_read_idx + idx->entries) % IVTV_MAX_PGM_INDEX;
 		break;