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....@googlemail.com>
---
drivers/media/usb/em28xx/em28xx-video.c | 29 +++++++++--------------------
drivers/media/usb/em28xx/em28xx.h | 3 +++
2 Dateien geändert, 12 Zeilen hinzugefügt(+), 20 Zeilen entfernt(-)
diff --git a/drivers/media/usb/em28xx/em28xx-video.c
b/drivers/media/usb/em28xx/em28xx-video.c
index 70bc562..60df756 100644
--- 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_usbdbg("dev is null\n");
@@ -268,6 +270,7 @@ static void em28xx_copy_vbi(struct em28xx *dev,
em28xx_usbdbg("p is null\n");
return;
}
+ outp = buf->vb_buf;
if (outp == NULL) {
em28xx_usbdbg("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
--- 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 {
--
1.7.10.4
--
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