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    SubjectRe: [RFC] What are the goals for the architecture of an in-kernel IR system?
    On Tue, Dec 15, 2009 at 8:33 AM, Mauro Carvalho Chehab
    <> wrote:
    > Pavel Machek wrote:
    >>>> That is why I think we should go the other way around - introduce the
    >>>> core which receivers could plug into and decoder framework and once it
    >>>> is ready register lirc-dev as one of the available decoders.
    >>> I've committed already some IR restruct code on my linux-next -git tree:
    >>> The code there basically moves the input/evdev registering code and
    >>> scancode/keycode management code into a separate ir-core module.
    >>> To make my life easy, I've moved the code temporarily into drivers/media/IR.
    >>> This way, it helps me to move V4L specific code outside ir-core and to later
    >>> use it for DVB. After having it done, probably the better is to move it to
    >>> be under /drivers or /drivers/input.
    >> Well, -next is for stuff to be merged into 2.6.34. You are quite an
    >> optimist.
    >>                                                                       Pavel
    > Well, we need those changes anyway for the in-kernel drivers, and I'm not seeing
    > on the current patches any reason for not having them for 2.6.34.
    > I've added all the ir-core patches I did so far at linux-next. This helps people
    > to review and contribute.
    > The patches are already working with the in-kernel em28xx driver, allowing to
    > replace the keycode table and the protocol used by the hardware IR decoder.
    > I tested here by replacing an RC-5 based IR table (Hauppauge Grey) by a NEC
    > based IR table (Terratec Cinergy XS remote controller).
    > The current Remote Controller core module (ir-core) is currently doing:
    >        - Implementation of the existing EVIO[G|S]KEYCODE, expanding/feeing memory
    > dynamically, based on the needed size for scancode/keycode table;
    >        - scancodes can be up to 16 bits currently;
    >        - sysfs is registering /sys/class/irrcv and creating one branch for each
    > different RC receiver, numbering from irrcv0 to irrcv255;
    >        - one irrcv note is created: current_protocol;
    >        - reading /sys/class/irrcv/irrcv*/current_protocol returns the protocol
    > currently used by the driver;
    >        - writing to /sys/class/irrcv/irrcv*/current_protocol changes the protocol
    > to a new one, by calling a callback, asking the driver to change the protocol. If
    > the protocol is not support, it returns -EINVAL;
    >        - all V4L drivers are already using ir-core;
    >        - em28xx driver is implementing current_protocol show/store support.
    > TODO:

    I'd add a pulse based receiver like a MSMCE to make sure the core API is right.
    MSME has transmit hardware too.

    What about creating multiple evdev devices with their own keymaps off
    from a single receiver? That's a key part of making multi-function
    remotes work.

    >        1) Port DVB drivers to use ir-core, removing the duplicated (and incomplete
    >          - as table size can't change on DVB's implementation) code that exists there;
    >        2) add current_protocol support on other drivers;
    >        3) link the corresponding input/evdev interfaces with /sys/class/irrcv/irrcv*;
    >        4) make the keytable.c application aware of the sysfs vars;
    >        5) add an attribute to uniquely identify a remote controller;
    >        6) write or convert an existing application to load IR tables at runtime;
    >        7) get the complete 16-bit scancodes used by V4L drivers;
    >        8) add decoder/lirc_dev glue to ir-core;
    >        9) add lirc_dev module and in-kernel decoders;
    >        10) extend keycode table replacement to support big/variable sized scancodes;
    >        11) rename IR->RC;
    >        12) redesign or remove ir-common module. It currently handles in-kernel
    >            keycode tables and a few helper routines for raw pulse/space decode;
    >        13) move drivers/media/IR to a better place;
    > comments:
    >        Tasks (1) to (6) for sure can happen to 2.6.34, depending on people's spare
    > time for it;
    >        (7) is probably the more complex task, since it requires to re-test all in-kernel
    > supported remote controlle scancode/keycode tables, to get the complete IR keycode
    > and rewrite the getkeycode functions that are currently masking the IR code into 7 bits.
    > We'll need users help on this task, but this can be done gradually, like I did with
    > two RC keytables on em28xx driver, while preserving the other keytables as-is.
    >        (8) I suggest that this glue will be submitted together with lirc_dev patch
    > series, as the biggest client for it is lirc. In principle, kfifo seems the better
    > interface for lirc_dev -> decoders interface. For the decoders -> RC core interface,
    > there's an interface already used on V4L drivers, provided by ir-common, using evdev
    > kernel API. This may need some review.
    >        (9) depends on lirc API discusions. My proposal is that people submit an RFC
    > with the lirc API reviewed to the ML's, for people to ack/nack/comment. After that,
    > re-submit the lirc_dev module integrating it into ir-core and with the reviewed API;
    >        (10) depends on EVIO[G|S]KEYCODE discussions we've already started. I did a proposal
    > about it. I'll review, based on the comments and re-submit it;
    >        (11) if none is against renaming IR as RC, I'll do it on a next patch;
    >        (12) depends on having lirc_dev added, for the removal of ir-functions.c. With
    > respect to the keytables, maybe one interesting alternative is to use a logic close to
    > nls tables that exists at fs, allowing to individually insert or remove an IR keytable
    > in-kernel.
    >        (13) has low priority. While not finishing the DVB integration with RC core
    > and reviewing the remaining bits of the ir-common module.
    > Cheers,
    > Mauro.

    Jon Smirl
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