Error compiling driver - unknown field specified in initializer

Question

I'm trying to compile a video driver on Ubuntu 10.04 LTS, here's the error:

**************************************************************************
* Building Techwell TW686x driver...                                     *
* Type "make help" for a list of available targets.                      *
**************************************************************************

make -C /lib/modules/`uname -r`/build M="/home/v4/driver-686x-0.1.1" clean
make[1]: Entering directory `/usr/src/linux-headers-2.6.32-43-generic'
make[1]: Leaving directory `/usr/src/linux-headers-2.6.32-43-generic'
make -C /lib/modules/`uname -r`/build M="/home/v4/driver-686x-0.1.1" modules
make[1]: Entering directory `/usr/src/linux-headers-2.6.32-43-generic'
  CC [M]  /home/v4/driver-686x-0.1.1/tw686x-core.o
  CC [M]  /home/v4/driver-686x-0.1.1/tw686x-video.o
  CC [M]  /home/v4/driver-686x-0.1.1/tw686x-i2c.o
  CC [M]  /home/v4/driver-686x-0.1.1/tw686x-device.o
  CC [M]  /home/v4/driver-686x-0.1.1/i2c-sw.o
  CC [M]  /home/v4/driver-686x-0.1.1/tw686x-alsa.o
  CC [M]  /home/v4/driver-686x-0.1.1/videobuf-dma-contig-tw.o
/home/v4/driver-686x-0.1.1/videobuf-dma-contig-tw.c:341: warning: initialization from incompatible pointer type
/home/v4/driver-686x-0.1.1/videobuf-dma-contig-tw.c:343: warning: initialization from incompatible pointer type
/home/v4/driver-686x-0.1.1/videobuf-dma-contig-tw.c:344: error: unknown field ‘vaddr’ specified in initializer
/home/v4/driver-686x-0.1.1/videobuf-dma-contig-tw.c:344: warning: excess elements in struct initializer
/home/v4/driver-686x-0.1.1/videobuf-dma-contig-tw.c:344: warning: (near initialization for ‘qops’)
/home/v4/driver-686x-0.1.1/videobuf-dma-contig-tw.c: In function ‘videobuf_queue_dma_contig_init_tw’:
/home/v4/driver-686x-0.1.1/videobuf-dma-contig-tw.c:357: warning: passing argument 2 of ‘videobuf_queue_core_init’ discards qualifiers from pointer target type
include/media/videobuf-core.h:197: note: expected ‘struct videobuf_queue_ops *’ but argument is of type ‘const struct videobuf_queue_ops *’
make[2]: *** [/home/v4/driver-686x-0.1.1/videobuf-dma-contig-tw.o] Error 1
make[1]: *** [_module_/home/v4/driver-686x-0.1.1] Error 2
make[1]: Leaving directory `/usr/src/linux-headers-2.6.32-43-generic'
make: *** [modules] Error 2

My kernel is 2.6.32-43. My C is very rusty, so I'm asking the gurus. From what I can see, the problem refers to variable videobuf_queue_ops in file videobuf-core.h, which i found in these locations:

/usr/src/linux-headers-2.6.24-24/include/media/videobuf-core.h
/usr/src/linux-headers-2.6.32-43/include/media/videobuf-core.h
/usr/src/linux-headers-2.6.24-32/include/media/videobuf-core.h

Here's the offending file (extract) videobuf-dma-contig-tw.c:

static struct videobuf_qtype_ops qops = {
    .magic        = MAGIC_QTYPE_OPS,

    .alloc        = __videobuf_alloc,
    .iolock       = __videobuf_iolock,
    .mmap_mapper  = __videobuf_mmap_mapper,
    .vaddr        = __videobuf_to_vaddr,
};

The definition of videobuf_qtype_ops in the header file looks like this :

struct videobuf_queue_ops {
    int (*buf_setup)(struct videobuf_queue *q,
             unsigned int *count, unsigned int *size);
    int (*buf_prepare)(struct videobuf_queue *q,
               struct videobuf_buffer *vb,
               enum v4l2_field field);
    void (*buf_queue)(struct videobuf_queue *q,
              struct videobuf_buffer *vb);
    void (*buf_release)(struct videobuf_queue *q,
                struct videobuf_buffer *vb);
};

#define MAGIC_QTYPE_OPS 0x12261003

/* Helper operations - device type dependent */
struct videobuf_qtype_ops {
    u32                     magic;

    void *(*alloc)      (size_t size);
    void *(*vmalloc)    (struct videobuf_buffer *buf);
    int (*iolock)       (struct videobuf_queue* q,
                 struct videobuf_buffer *vb,
                 struct v4l2_framebuffer *fbuf);
    int (*mmap)     (struct videobuf_queue *q,
                 unsigned int *count,
                 unsigned int *size,
                 enum v4l2_memory memory);
    int (*sync)     (struct videobuf_queue* q,
                 struct videobuf_buffer *buf);
    int (*video_copy_to_user)(struct videobuf_queue *q,
                 char __user *data,
                 size_t count,
                 int nonblocking);
    int (*copy_stream)  (struct videobuf_queue *q,
                 char __user *data,
                 size_t count,
                 size_t pos,
                 int vbihack,
                 int nonblocking);
    int (*mmap_free)    (struct videobuf_queue *q);
    int (*mmap_mapper)  (struct videobuf_queue *q,
                struct vm_area_struct *vma);
};

Should I change this header file? I'm not sure what the fix is, or whether I should even be changing Linux files - scary stuff!

Thanks for your help.

Answer 1

For some reason the compiler doesn't like this part:

static struct videobuf_qtype_ops qops = {
    .magic        = MAGIC_QTYPE_OPS,

    .alloc        = __videobuf_alloc,
    .iolock       = __videobuf_iolock,
    .mmap_mapper  = __videobuf_mmap_mapper,
    .vaddr        = __videobuf_to_vaddr,
};

The compiler told you the line number where the error had occurred:

videobuf-dma-contig-tw.c:344: error: unknown field ‘vaddr’ specified in initializer

Now the question is why there isn't a vaddr member in struct videobuf_qtype_ops. It could be under #if, but I don't know for sure. struct videobuf_qtype_ops isn't defined in this file.

You should've looked at this yourself. Posting lots of irrelevant code isn't a good use of people's time.

Answer 2

This part alone

/home/v4/driver-686x-0.1.1/videobuf-dma-contig-tw.c:343: warning: initialization from incompatible pointer type
/home/v4/driver-686x-0.1.1/videobuf-dma-contig-tw.c:344: error: unknown field ‘vaddr’ specified in initializer
/home/v4/driver-686x-0.1.1/videobuf-dma-contig-tw.c:344: warning: excess elements in struct initializer

tells us that the initializer and the struct are using different types, different field names, and different number of elements.

Definitely not the correct include file. :-)

You will have to figure out what version you should use, and make sure that one is in the include path (and not the others).