[media] gspca - sonixj: Better scanning of isochronous packets (a4a3076f) · Commits · e / devices / android_kernel_fairphone_FP4

drivers/media/video/gspca/sonixj.c

+93 −26

Original line number	Diff line number	Diff line
		@@ -57,6 +57,8 @@ struct sd {
		atomic_t avg_lum;
		u32 exposure;

		s8 short_mark;

		u8 quality; /* image quality */
		#define QUALITY_MIN 60
		#define QUALITY_MAX 95
		@@ -2787,39 +2789,104 @@ static void sd_pkt_scan(struct gspca_dev *gspca_dev,
		int len) /* iso packet length */
		{
		struct sd sd = (struct sd ) gspca_dev;
		int sof;

		/* the image ends on a 64 bytes block starting with
		* ff d9 ff ff 00 c4 c4 96
		* and followed by various information including luminosity */
		/* this block may be splitted between two packets */
		/* a new image always starts in a new packet */
		switch (gspca_dev->last_packet_type) {
		case DISCARD_PACKET: /* restart image building */
		sof = len - 64;
		if (sof >= 0 && data[sof] == 0xff && data[sof + 1] == 0xd9)
		gspca_frame_add(gspca_dev, LAST_PACKET, NULL, 0);
		int i;

		/*
		* A frame ends on the marker
		* ff ff 00 c4 c4 96 ..
		* which is 62 bytes long and is followed by various information
		* including statuses and luminosity.
		*
		* A marker may be splitted on two packets.
		*
		* The 6th byte of a marker contains the bits:
		* 0x08: USB full
		* 0xc0: frame sequence
		* When the bit 'USB full' is set, the frame must be discarded;
		* this is also the case when the 2 bytes before the marker are
		* not the JPEG end of frame ('ff d9').
		*/

		/*fixme: assumption about the following code:
		* - there can be only one marker in a packet
		*/

		/* skip the remaining bytes of a short marker */
		i = sd->short_mark;
		if (i != 0) {
		sd->short_mark = 0;
		if (i < 0 /* if 'ff' at end of previous packet */
		&& data[0] == 0xff
		&& data[1] == 0x00)
		goto marker_found;
		if (data[0] == 0xff && data[1] == 0xff) {
		i = 0;
		goto marker_found;
		}
		len -= i;
		if (len <= 0)
		return;
		case LAST_PACKET: /* put the JPEG 422 header */
		data += i;
		}

		/* search backwards if there is a marker in the packet */
		for (i = len - 1; --i >= 0; ) {
		if (data[i] != 0xff) {
		i--;
		continue;
		}
		if (data[i + 1] == 0xff) {

		/* (there may be 'ff ff' inside a marker) */
		if (i + 2 >= len \|\| data[i + 2] == 0x00)
		goto marker_found;
		}
		}

		/* no marker found */
		/* add the JPEG header if first fragment */
		if (data[len - 1] == 0xff)
		sd->short_mark = -1;
		if (gspca_dev->last_packet_type == LAST_PACKET)
		gspca_frame_add(gspca_dev, FIRST_PACKET,
		sd->jpeg_hdr, JPEG_HDR_SZ);
		break;
		}
		gspca_frame_add(gspca_dev, INTER_PACKET, data, len);

		data = gspca_dev->image;
		if (data == NULL)
		return;
		sof = gspca_dev->image_len - 64;
		if (data[sof] != 0xff
		\|\| data[sof + 1] != 0xd9)

		/* marker found */
		/* if some error, discard the frame */
		marker_found:
		if (i > 2) {
		if (data[i - 2] != 0xff \|\| data[i - 1] != 0xd9) {
		gspca_dev->last_packet_type = DISCARD_PACKET;
		}
		} else if (i + 6 < len) {
		if (data[i + 6] & 0x08) {
		gspca_dev->last_packet_type = DISCARD_PACKET;
		}
		}

		gspca_frame_add(gspca_dev, LAST_PACKET, data, i);

		/* if the marker is smaller than 62 bytes,
		* memorize the number of bytes to skip in the next packet */
		if (i + 62 > len) { /* no more usable data */
		sd->short_mark = i + 62 - len;
		return;
		}

		/* end of image found - remove the trailing data */
		gspca_dev->image_len = sof + 2;
		gspca_frame_add(gspca_dev, LAST_PACKET, NULL, 0);
		if (sd->ag_cnt >= 0)
		set_lum(sd, data + sof + 2);
		set_lum(sd, data + i);

		/* if more data, start a new frame */
		i += 62;
		if (i < len) {
		data += i;
		len -= i;
		gspca_frame_add(gspca_dev, FIRST_PACKET,
		sd->jpeg_hdr, JPEG_HDR_SZ);
		gspca_frame_add(gspca_dev, INTER_PACKET, data, len);
		}
		}

		static int sd_set_jcomp(struct gspca_dev *gspca_dev,