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    SubjectRe: [RFC v2] Another approach to IR
    Andy Walls wrote:
    > On Wed, 2009-12-02 at 14:55 -0500, Jarod Wilson wrote:
    >> On Dec 2, 2009, at 2:33 PM, Mauro Carvalho Chehab wrote:
    >>
    >>> Dmitry Torokhov wrote:
    >> ...
    >>>>>> (for each remote/substream that they can recognize).
    >>>>> I'm assuming that, by remote, you're referring to a remote receiver (and not to
    >>>>> the remote itself), right?
    >>>> If we could separate by remote transmitter that would be the best I
    >>>> think, but I understand that it is rarely possible?
    >>> IMHO, the better is to use a separate interface for the IR transmitters,
    >>> on the devices that support this feature. There are only a few devices
    >>> I'm aware of that are able to transmit IR codes.
    >> If I'm thinking clearly, there are only three lirc kernel drivers that
    >> support transmit, lirc_mceusb, lirc_zilog and lirc_serial. The mceusb
    >> driver was posted, so I won't rehash what it is here. The zilog driver
    >> binds to a Zilog z80 microprocessor thingy (iirc) exposed via i2c,
    >> found on many Hauppauge v4l/dvb devices (PVR-150, HVR-1600, HD-PVR,
    >> etc). The serial driver is fairly self-explanatory as well.
    >>
    >> There are also a few userspace-driven devices that do transmit, but
    >> I'm assuming they're (currently) irrelevant to this discussion.
    >
    >
    > I've got the CX23888 integrated IR Rx done and Tx nearly done. I was
    > waiting to see how kfifo and lirc_dev panned out before making the
    > interface to userspace.
    >
    > The CX23885, CX23418, and CX2584x integrated IR is essentially the same.
    > I hope to have CX23885 IR done by Christmas.
    >
    > Both of those IR devices are/will be encapsulated in a v4l2_subdevice
    > object internally. I was going to write lirc_v4l glue between the
    > v4l2_device/v4l2_subdev_ir_ops and lirc_dev.
    >
    > As for the the I2C chips, I was going to go back and encapsulate those
    > in the v4l2_subdevice object as well, so then my notional lirc_v4l could
    > pick those up too. The I2C subsystem only allows one binding to an I2C
    > client address/name on a bus. So without some new glue like a notional
    > lirc_v4l, it *may* be hard to share between ir-kbd-i2c and lirc_i2c and
    > lirc_zilog.

    Maybe you're having a bad time because you may be trying to integrate lirc
    at the wrong place.

    All devices at V4L tree including ir-kbd-i2c use ir-common.ko
    (at /drivers/media/common tree) module to communicate to IR's.
    I'm preparing some patches to extend this also to dvb-usb devices
    (that uses a close enough infrastructure).

    Also, most of the decoding code are there, in a form of helper routines.

    As the idea is to provide lirc interface to all devices that can work with
    raw pulse/space, the proper place is to write a subroutine there that, once
    called, will make those pulse/space raw codes available to lirc and will
    call the needed decoders to export them also to evdev.

    The code at ir-common module was originally built to be used by V4L, but I'm
    porting the code there to be generic enough to be a library that can be used
    by other drivers. So, lirc_zilog and other lirc devices that will need to open
    evdev interfaces after running a decoder can use them.

    Due to that, we shouldn't add v4l2_subdevice there. Nothing prevents to create
    a v4l2-ir-subdev glue if you want to see the IR's as subdevices, but this should
    be implemented as a separate module.

    Cheers,
    Mauro.


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