[media] em28xx: move the em2710/em2750/em28xx specific frame data processing code to a separate function

em28xx_urb_data_copy() actually consists of two parts:
USB urb processing (checks, data extraction) and frame data packet processing.
Move the latter to a separate function and call it from em28xx_urb_data_copy()
for each data packet.
The em25xx, em2760, em2765 (and likely em277x) chip variants are using a
different frame data format, for which support will be added later with
another function.
This reduces the size of em28xx_urb_data_copy() and makes the code much more
readable. While we're at it, clean up the code a bit (rename some variables to
something more meaningful, improve some comments etc.)

Signed-off-by: Frank Schäfer <fschaefer.oss@googlemail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 90 insertions, 80 deletions

diff --git a/drivers/media/usb/em28xx/em28xx-video.c b/drivers/media/usb/em28xx/em28xx-video.c
index a1f6de0f1b3b..133e6b0a5c7d 100644
--- a/drivers/media/usb/em28xx/em28xx-video.c
+++ b/drivers/media/usb/em28xx/em28xx-video.c
@@ -379,15 +379,90 @@ finish_field_prepare_next(struct em28xx *dev,
         return buf;
 }
 
-/* Processes and copies the URB data content (video and VBI data) */
-static inline int em28xx_urb_data_copy(struct em28xx *dev, struct urb *urb)
+/*
+ * Process data packet according to the em2710/em2750/em28xx frame data format
+ */
+static inline void process_frame_data_em28xx(struct em28xx *dev,
+                                             unsigned char *data_pkt,
+                                             unsigned int  data_len)
 {
-        struct em28xx_buffer    *buf, *vbi_buf;
+        struct em28xx_buffer    *buf = dev->usb_ctl.vid_buf;
+        struct em28xx_buffer    *vbi_buf = dev->usb_ctl.vbi_buf;
         struct em28xx_dmaqueue  *dma_q = &dev->vidq;
         struct em28xx_dmaqueue  *vbi_dma_q = &dev->vbiq;
-        int xfer_bulk, num_packets, i, rc = 1;
-        unsigned int actual_length, len = 0;
-        unsigned char *p;
+
+        /* capture type 0 = vbi start
+           capture type 1 = vbi in progress
+           capture type 2 = video start
+           capture type 3 = video in progress */
+        if (data_len >= 4) {
+                /* NOTE: Headers are always 4 bytes and
+                 * never split across packets */
+                if (data_pkt[0] == 0x88 && data_pkt[1] == 0x88 &&
+                    data_pkt[2] == 0x88 && data_pkt[3] == 0x88) {
+                        /* Continuation */
+                        data_pkt += 4;
+                        data_len -= 4;
+                } else if (data_pkt[0] == 0x33 && data_pkt[1] == 0x95) {
+                        /* Field start (VBI mode) */
+                        dev->capture_type = 0;
+                        dev->vbi_read = 0;
+                        em28xx_isocdbg("VBI START HEADER !!!\n");
+                        dev->top_field = !(data_pkt[2] & 1);
+                        data_pkt += 4;
+                        data_len -= 4;
+                } else if (data_pkt[0] == 0x22 && data_pkt[1] == 0x5a) {
+                        /* Field start (VBI disabled) */
+                        dev->capture_type = 2;
+                        em28xx_isocdbg("VIDEO START HEADER !!!\n");
+                        dev->top_field = !(data_pkt[2] & 1);
+                        data_pkt += 4;
+                        data_len -= 4;
+                }
+        }
+        /* NOTE: With bulk transfers, intermediate data packets
+         * have no continuation header */
+
+        if (dev->capture_type == 0) {
+                vbi_buf = finish_field_prepare_next(dev, vbi_buf, vbi_dma_q);
+                dev->usb_ctl.vbi_buf = vbi_buf;
+                dev->capture_type = 1;
+        }
+
+        if (dev->capture_type == 1) {
+                int vbi_size = dev->vbi_width * dev->vbi_height;
+                int vbi_data_len = ((dev->vbi_read + data_len) > vbi_size) ?
+                                   (vbi_size - dev->vbi_read) : data_len;
+
+                /* Copy VBI data */
+                if (vbi_buf != NULL)
+                        em28xx_copy_vbi(dev, vbi_buf, data_pkt, vbi_data_len);
+                dev->vbi_read += vbi_data_len;
+
+                if (vbi_data_len < data_len) {
+                        /* Continue with copying video data */
+                        dev->capture_type = 2;
+                        data_pkt += vbi_data_len;
+                        data_len -= vbi_data_len;
+                }
+        }
+
+        if (dev->capture_type == 2) {
+                buf = finish_field_prepare_next(dev, buf, dma_q);
+                dev->usb_ctl.vid_buf = buf;
+                dev->capture_type = 3;
+        }
+
+        if (dev->capture_type == 3 && buf != NULL && data_len > 0)
+                em28xx_copy_video(dev, buf, data_pkt, data_len);
+}
+
+/* Processes and copies the URB data content (video and VBI data) */
+static inline int em28xx_urb_data_copy(struct em28xx *dev, struct urb *urb)
+{
+        int xfer_bulk, num_packets, i;
+        unsigned char *usb_data_pkt;
+        unsigned int usb_data_len;
 
         if (!dev)
                 return 0;
@@ -400,9 +475,6 @@ static inline int em28xx_urb_data_copy(struct em28xx *dev, struct urb *urb)
 
         xfer_bulk = usb_pipebulk(urb->pipe);
 
-        buf = dev->usb_ctl.vid_buf;
-        vbi_buf = dev->usb_ctl.vbi_buf;
-
         if (xfer_bulk) /* bulk */
                 num_packets = 1;
         else /* isoc */
@@ -410,9 +482,9 @@ static inline int em28xx_urb_data_copy(struct em28xx *dev, struct urb *urb)
 
         for (i = 0; i < num_packets; i++) {
                 if (xfer_bulk) { /* bulk */
-                        actual_length = urb->actual_length;
+                        usb_data_len = urb->actual_length;
 
-                        p = urb->transfer_buffer;
+                        usb_data_pkt = urb->transfer_buffer;
                 } else { /* isoc */
                         if (urb->iso_frame_desc[i].status < 0) {
                                 print_err_status(dev, i,
@@ -421,87 +493,25 @@ static inline int em28xx_urb_data_copy(struct em28xx *dev, struct urb *urb)
                                         continue;
                         }
 
-                        actual_length = urb->iso_frame_desc[i].actual_length;
-                        if (actual_length > dev->max_pkt_size) {
+                        usb_data_len = urb->iso_frame_desc[i].actual_length;
+                        if (usb_data_len > dev->max_pkt_size) {
                                 em28xx_isocdbg("packet bigger than packet size");
                                 continue;
                         }
 
-                        p = urb->transfer_buffer +
-                            urb->iso_frame_desc[i].offset;
+                        usb_data_pkt = urb->transfer_buffer +
+                                       urb->iso_frame_desc[i].offset;
                 }
 
-                if (actual_length == 0) {
+                if (usb_data_len == 0) {
                         /* NOTE: happens very often with isoc transfers */
                         /* em28xx_usbdbg("packet %d is empty",i); - spammy */
                         continue;
                 }
 
-                /* capture type 0 = vbi start
-                   capture type 1 = vbi in progress
-                   capture type 2 = video start
-                   capture type 3 = video in progress */
-                len = actual_length;
-                if (len >= 4) {
-                        /* NOTE: headers are always 4 bytes and
-                         * never split across packets */
-                        if (p[0] == 0x33 && p[1] == 0x95) {
-                                dev->capture_type = 0;
-                                dev->vbi_read = 0;
-                                em28xx_isocdbg("VBI START HEADER!!!\n");
-                                dev->top_field = !(p[2] & 1);
-                                p += 4;
-                                len -= 4;
-                        } else if (p[0] == 0x88 && p[1] == 0x88 &&
-                                   p[2] == 0x88 && p[3] == 0x88) {
-                                /* continuation */
-                                p += 4;
-                                len -= 4;
-                        } else if (p[0] == 0x22 && p[1] == 0x5a) {
-                                /* start video */
-                                dev->capture_type = 2;
-                                dev->top_field = !(p[2] & 1);
-                                p += 4;
-                                len -= 4;
-                        }
-                }
-                /* NOTE: with bulk transfers, intermediate data packets
-                 * have no continuation header */
-
-                if (dev->capture_type == 0) {
-                        vbi_buf = finish_field_prepare_next(dev, vbi_buf, vbi_dma_q);
-                        dev->usb_ctl.vbi_buf = vbi_buf;
-                        dev->capture_type = 1;
-                }
-
-                if (dev->capture_type == 1) {
-                        int vbi_size = dev->vbi_width * dev->vbi_height;
-                        int vbi_data_len = ((dev->vbi_read + len) > vbi_size) ?
-                                           (vbi_size - dev->vbi_read) : len;
-
-                        /* Copy VBI data */
-                        if (vbi_buf != NULL)
-                                em28xx_copy_vbi(dev, vbi_buf, p, vbi_data_len);
-                        dev->vbi_read += vbi_data_len;
-
-                        if (vbi_data_len < len) {
-                                /* Continue with copying video data */
-                                dev->capture_type = 2;
-                                p += vbi_data_len;
-                                len -= vbi_data_len;
-                        }
-                }
-
-                if (dev->capture_type == 2) {
-                        buf = finish_field_prepare_next(dev, buf, dma_q);
-                        dev->usb_ctl.vid_buf = buf;
-                        dev->capture_type = 3;
-                }
-
-                if (buf != NULL && dev->capture_type == 3 && len > 0)
-                        em28xx_copy_video(dev, buf, p, len);
+                process_frame_data_em28xx(dev, usb_data_pkt, usb_data_len);
         }
-        return rc;
+        return 1;
 }