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[104.188.17.28]) by smtp.gmail.com with ESMTPSA id d26sm13917312pgv.66.2020.01.13.09.24.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 13 Jan 2020 09:24:56 -0800 (PST) Date: Mon, 13 Jan 2020 09:24:53 -0800 From: Bjorn Andersson To: Arnaud Pouliquen Cc: Ohad Ben-Cohen , linux-kernel@vger.kernel.org, linux-remoteproc@vger.kernel.org, linux-arm-msm@vger.kernel.org, Suman Anna , Fabien DESSENNE , linux-stm32@st-md-mailman.stormreply.com Subject: Re: [PATCH v2] rpmsg: core: add API to get MTU Message-ID: <20200113172453.GQ738324@yoga> References: <20191113172249.32412-1-arnaud.pouliquen@st.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191113172249.32412-1-arnaud.pouliquen@st.com> User-Agent: Mutt/1.12.2 (2019-09-21) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 13 Nov 09:22 PST 2019, Arnaud Pouliquen wrote: > Return the rpmsg buffer MTU for sending message, so rpmsg users > can split a long message in several sub rpmsg buffers. > I won't merge this new api without a client, and I'm still concerned about the details. > Signed-off-by: Arnaud Pouliquen > --- > V1 to V2 > > V1 patch:https://lore.kernel.org/patchwork/patch/1124684/ > - Change patch title, > - as not solution today to support MTU on GLINK make ops optional, > RPMsg client API returns -ENOTSUPP in this case, > - suppress smd and glink patches. That's ok. > --- > drivers/rpmsg/rpmsg_core.c | 21 +++++++++++++++++++++ > drivers/rpmsg/rpmsg_internal.h | 2 ++ > drivers/rpmsg/virtio_rpmsg_bus.c | 10 ++++++++++ > include/linux/rpmsg.h | 10 ++++++++++ > 4 files changed, 43 insertions(+) > > diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c > index e330ec4dfc33..a6ef54c4779a 100644 > --- a/drivers/rpmsg/rpmsg_core.c > +++ b/drivers/rpmsg/rpmsg_core.c > @@ -283,6 +283,27 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst, > } > EXPORT_SYMBOL(rpmsg_trysend_offchannel); > > +/** > + * rpmsg_get_mtu() - get maximum transmission buffer size for sending message. > + * @ept: the rpmsg endpoint > + * > + * This function returns maximum buffer size available for a single message. > + * > + * Return: the maximum transmission size on success and an appropriate error > + * value on failure. Is the expectation that a call to rpmsg_send() with this size will eventually succeed? > + */ [..] > +static ssize_t virtio_rpmsg_get_mtu(struct rpmsg_endpoint *ept) > +{ > + struct rpmsg_device *rpdev = ept->rpdev; > + struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev); > + > + return vch->vrp->buf_size - sizeof(struct rpmsg_hdr); I'm still under the impression that the rpmsg protocol doesn't have to operate on fixed size messages. Would this then return vrp->num_bufs * vrp->buf_size / 2 - sizeof(rpmsg_hdr)? > +} > + Regards, Bjorn