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Building capture device driver for dm6467T (kernel 2.6.32)

Shlomi Levi93913
Prodigy 10 points

Hi, we are migrating from DM6467 to DM6467T.

At the process we have migrated from MontaVista 2.6.18 to git 2.6.32 (all suplied by TI).

We are having trouble understanding how the vpif_capture driver knows that a buffer arrived on the BT656 lines.

More specifically, we are stuck on the 'dqbuf' at the videobuf.

Any help would be appreciated.

Thanks

  • 0
    Guru 11260 points

    Shlomi,

    We are having trouble understanding how the vpif_capture driver knows that a buffer arrived on the BT656 lines

    More specifically, we are stuck on the 'dqbuf' at the videobuf.

    you need to have brief understanding on how V4l2 driver works, in brief the general the capture device,

    say /dev/video0 and configures it for SD or HD,  appropriately the timings are set for SD 27Mhz and for HD 74.25MHz

    then we request the buffers from the driver, next the buffers are queued at this time the state to buffer is VIDEOBUF_QUEUED,

    The first buffer queued is stated as active buffer (to fill in data on start of stream on). To start capturing of frames streamon is called

    to start the capturing of frames,  The isr which is configured keeps on checking on and when complete buffer  is filled the state of that buffer

    is marked as VIDEOBUF_DONE and the next buffer is scheduled for the process and this continues... So now when you try to dqbuf it means

    it checks the buffer state is "VIDEOBUF_DONE" .

    For more understanding you can have a look at v4l2 driver core.

    The internal decoder tvp514X internal takes care of the standard if you connect appropriate input to it , the decoder will convert the captured

    analog data and store it to the buffer  and then the isr will be generated.

    Did you check wether the ISR is coming or not ?

    Regards,

    --Prabhakar Lad