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    SubjectRe: [PATCH] mailbox: add support for doorbell/signal mode controllers
    On Thu, Nov 2, 2017 at 3:42 AM, Bjorn Andersson
    <bjorn.andersson@linaro.org> wrote:
    > On Wed 01 Nov 11:03 PDT 2017, Jassi Brar wrote:
    >> On Wed, Nov 1, 2017 at 10:02 PM, Sudeep Holla <sudeep.holla@arm.com> wrote:
    > [..]
    >> >
    >> > This is rough idea I have on extending mailbox interface to support
    >> > the doorbell requirements.
    >> >
    >> What doorbell requirements does the api not support?
    >> QComm's APCS IPC is what you call a "doorbell" controller and is
    >> already supported by the API. It could run SCMI even easier than MHU
    >> (your controller).
    >>
    >
    > I agree; from a mbox consumer perspective a doorbell should be a mailbox
    > channel that when signalled will ring the bell, i.e. the message is not
    > significant and should not be provided by the client.
    >
    > If the message is significant and is not derived from the mailbox
    > channel (e.g. channel id -> bit in register) it is not a mailbox
    > doorbell, it's s regular mailbox used as a doorbell.
    >
    >
    > The potential improvement I see in the Qualcomm case is to wrap the
    > mbox_send_message(chan, NULL); mbox_client_txdone(chan, 0); calls in one
    > simple "mbox_ring_door_bell(chan)" - but I haven't investigated the
    > validity of this as a generic function.
    >
    If you remember I already suggested we can use the existing api to
    define a convenient helper ->
    https://www.spinics.net/lists/linux-soc/msg01781.html

    mailbox_client.h
    *******************
    void mbox_ring_doorbell(struct mbox_chan *chan, void *mssg)
    {
    (void)mbox_send_message(chan, mssg);
    mbox_client_txdone(chan, 0);
    }

    .... instead of adding a new api and modifying each driver.

    Cheers!

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