Hi Hans, Chris, any other developers working on the new DMA code,
I tried the trunk on my PPC ivtv machine and can't get it to capture
anything. MythTV complains that the driver has stopped recording, and
I get the following kernel message:
ivtv0 warning: encoder MPEG: Couldn't find start of buffer within
the first 256 bytes
Fortunately, ivtv-0.9.x works just fine on my PPC machine, so it must
be a new change in the trunk. I think the cause is the buffer
(pointer?) being byteswapped and the DMA_MAGIC_COOKIE never gets
found.... This could be a result of using a char instead of a
v4l2_buffer in ivtv_buffer in ivtv-driver.h. Typecasting chars to
pointers always result in endian issues....
trunk ivtv-irq.c 218: u32buf = (u32 *)buf->buf;
0.9 ivtv-irq.c 296: (u32 *)(buf->buffer.m.userptr)
trunk struct ivtv_buffer {
struct list_head list;
dma_addr_t dma_handle;
unsigned long b_flags;
char *buf; // leads to
endian issues...
u32 bytesused;
u32 readpos;
};
0.9 struct ivtv_buffer {
size_t readpos;
dma_addr_t dma_handle;
struct v4l2_buffer buffer; // conversion handled
by
v4l2_buffer!
struct list_head list;
unsigned long ts;
unsigned long b_flags;
unsigned long *page;
unsigned char **vpage;
};
The "0.9" way of doing the buffer looks much safer to me... hope this
helps.
- Rick
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