[media] em28xx: move caching of pointer to vmalloc memory in videobuf to struct em28x...

In the current code em28xx_urb_data_copy() caches the pointer to the vmalloc
memory in videobuf locally.
The alternative would be to call videobuf_to_vmalloc() for each processed USB
data packet (isoc USB transfers => 64 times per URB) in the em28xx_copy_*()
functions.
With the next commits, the data processing code will be split into functions
for serveral reasons:
- em28xx_urb_data_copy() is generally way to long, making it less readable
- there is code duplication between VBI and video data processing
- support for em25xx data processing (uses a different header and frame
  end signaling mechanism) will be added
This would require extensive usage of pointer-pointers, which usually makes the
code less readable and prone to bugs.
The better solution is to cache the pointer in struct em28xx_buffer.
This also improves consistency, because we already track the buffer fill count there.

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

diff --git a/drivers/media/usb/em28xx/em28xx-video.c b/drivers/media/usb/em28xx/em28xx-video.c
index 3a13a71..da59442 100644 (file)
--- a/drivers/media/usb/em28xx/em28xx-video.c
+++ b/drivers/media/usb/em28xx/em28xx-video.c
@@ -173,11 +173,12 @@ static inline void finish_buffer(struct em28xx *dev,
 static void em28xx_copy_video(struct em28xx *dev,
                              struct em28xx_buffer *buf,
                              unsigned char *p,
-                             unsigned char *outp, unsigned long len)
+                             unsigned long len)
 {
        void *fieldstart, *startwrite, *startread;
        int  linesdone, currlinedone, offset, lencopy, remain;
        int bytesperline = dev->width << 1;
+       unsigned char *outp = buf->vb_buf;
 
        if (buf->pos + len > buf->vb.size)
                len = buf->vb.size - buf->pos;
@@ -249,11 +250,12 @@ static void em28xx_copy_video(struct em28xx *dev,
 static void em28xx_copy_vbi(struct em28xx *dev,
                            struct em28xx_buffer *buf,
                            unsigned char *p,
-                           unsigned char *outp, unsigned long len)
+                           unsigned long len)
 {
        void *startwrite, *startread;
        int  offset;
        int bytesperline;
+       unsigned char *outp;
 
        if (dev == NULL) {
                em28xx_isocdbg("dev is null\n");
@@ -268,6 +270,7 @@ static void em28xx_copy_vbi(struct em28xx *dev,
                em28xx_isocdbg("p is null\n");
                return;
        }
+       outp = buf->vb_buf;
        if (outp == NULL) {
                em28xx_isocdbg("outp is null\n");
                return;
@@ -350,6 +353,7 @@ static inline struct em28xx_buffer *get_next_buf(struct em28xx *dev,
        outp = videobuf_to_vmalloc(&buf->vb);
        memset(outp, 0, buf->vb.size);
        buf->pos = 0;
+       buf->vb_buf = outp;
 
        return buf;
 }
@@ -362,7 +366,7 @@ static inline int em28xx_urb_data_copy(struct em28xx *dev, struct urb *urb)
        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, *outp = NULL, *vbioutp = NULL;
+       unsigned char *p;
 
        if (!dev)
                return 0;
@@ -376,12 +380,7 @@ 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;
-       if (buf != NULL)
-               outp = videobuf_to_vmalloc(&buf->vb);
-
        vbi_buf = dev->usb_ctl.vbi_buf;
-       if (vbi_buf != NULL)
-               vbioutp = videobuf_to_vmalloc(&vbi_buf->vb);
 
        if (xfer_bulk) /* bulk */
                num_packets = 1;
@@ -455,11 +454,6 @@ static inline int em28xx_urb_data_copy(struct em28xx *dev, struct urb *urb)
                                        finish_buffer(dev, vbi_buf);
                                vbi_buf = get_next_buf(dev, vbi_dma_q);
                                dev->usb_ctl.vbi_buf = vbi_buf;
-                               if (vbi_buf == NULL)
-                                       vbioutp = NULL;
-                               else
-                                       vbioutp =
-                                         videobuf_to_vmalloc(&vbi_buf->vb);
                        }
                        if (vbi_buf != NULL) {
                                vbi_buf->top_field = dev->top_field;
@@ -474,8 +468,7 @@ static inline int em28xx_urb_data_copy(struct em28xx *dev, struct urb *urb)
 
                        /* Copy VBI data */
                        if (vbi_buf != NULL)
-                               em28xx_copy_vbi(dev, vbi_buf, p, vbioutp,
-                                               vbi_data_len);
+                               em28xx_copy_vbi(dev, vbi_buf, p, vbi_data_len);
                        dev->vbi_read += vbi_data_len;
 
                        if (vbi_data_len < len) {
@@ -493,10 +486,6 @@ static inline int em28xx_urb_data_copy(struct em28xx *dev, struct urb *urb)
                                        finish_buffer(dev, buf);
                                buf = get_next_buf(dev, dma_q);
                                dev->usb_ctl.vid_buf = buf;
-                               if (buf == NULL)
-                                       outp = NULL;
-                               else
-                                       outp = videobuf_to_vmalloc(&buf->vb);
                        }
                        if (buf != NULL) {
                                buf->top_field = dev->top_field;
@@ -505,7 +494,7 @@ static inline int em28xx_urb_data_copy(struct em28xx *dev, struct urb *urb)
                }
 
                if (buf != NULL && dev->capture_type == 3 && len > 0)
-                       em28xx_copy_video(dev, buf, p, outp, len);
+                       em28xx_copy_video(dev, buf, p, len);
        }
        return rc;
 }

diff --git a/drivers/media/usb/em28xx/em28xx.h b/drivers/media/usb/em28xx/em28xx.h
index 7507aa6..062841e 100644 (file)
--- a/drivers/media/usb/em28xx/em28xx.h
+++ b/drivers/media/usb/em28xx/em28xx.h
@@ -258,6 +258,9 @@ struct em28xx_buffer {
        unsigned int pos;
        /* NOTE; in interlaced mode, this value is reset to zero at
         * the start of each new field (not frame !)               */
+
+       /* pointer to vmalloc memory address in vb */
+       char *vb_buf;
 };
 
 struct em28xx_dmaqueue {