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From:   Mathieu Poirier <mathieu.poirier@linaro.org>
Date:   Mon, 18 Jul 2022 10:54:30 -0600
Message-ID: <CANLsYkxBZ+4its5sUPJExnenU8dgttcUwdsBApwC_nYMLmsmHg@mail.gmail.com>
Subject: Re: [PATCH 0/4] Introduction of rpmsg_rx_done
To:     Arnaud POULIQUEN <arnaud.pouliquen@foss.st.com>
Cc:     Chris Lew <quic_clew@quicinc.com>, bjorn.andersson@linaro.org,
        linux-remoteproc@vger.kernel.org, linux-arm-msm@vger.kernel.org,
        linux-kernel@vger.kernel.org
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On Mon, 18 Jul 2022 at 02:26, Arnaud POULIQUEN
<arnaud.pouliquen@foss.st.com> wrote:
>
> Hello Chris,
>
> On 6/8/22 03:16, Chris Lew wrote:
> > This series proposes an implementation for the rpmsg framework to do
> > deferred cleanup of buffers provided in the rx callback. The current
> > implementation assumes that the client is done with the buffer after
> > returning from the rx callback.
> >
> > In some cases where the data size is large, the client may want to
> > avoid copying the data in the rx callback for later processing. This
> > series proposes two new facilities for signaling that they want to
> > hold on to a buffer after the rx callback.
> > They are:
> >  - New API rpmsg_rx_done() to tell the rpmsg framework the client is
> >    done with the buffer
> >  - New return codes for the rx callback to signal that the client will
> >    hold onto a buffer and later call rpmsg_rx_done()
> >
> > This series implements the qcom_glink_native backend for these new
> > facilities.
>
> The API you proposed seems to me quite smart and adaptable to the rpmsg
> virtio backend.
>
> My main concern is about the release of the buffer when the endpoint
> is destroyed.
>
> Does the buffer release should be handled by each services or by the
> core?
>
> I wonder if the buffer list could be managed by the core part by adding
> the list in the rpmsg_endpoint structure. On destroy the core could call
> the rx_done for each remaining buffers in list...
>
> I let Bjorn and Mathieu advise on this...

Thanks for taking a look Arnaud.  I'll get to this sortly.

>
> Thanks,
> Arnaud
>
> >
> > Chris Lew (4):
> >   rpmsg: core: Add rx done hooks
> >   rpmsg: char: Add support to use rpmsg_rx_done
> >   rpmsg: glink: Try to send rx done in irq
> >   rpmsg: glink: Add support for rpmsg_rx_done
> >
> >  drivers/rpmsg/qcom_glink_native.c | 112 ++++++++++++++++++++++++++++++--------
> >  drivers/rpmsg/rpmsg_char.c        |  50 ++++++++++++++++-
> >  drivers/rpmsg/rpmsg_core.c        |  20 +++++++
> >  drivers/rpmsg/rpmsg_internal.h    |   1 +
> >  include/linux/rpmsg.h             |  24 ++++++++
> >  5 files changed, 183 insertions(+), 24 deletions(-)
> >