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Subject: Re: [PATCH 0/4] rpmsg: char: introduce the rpmsg-raw channel
To:     Mathieu Poirier <mathieu.poirier@linaro.org>
CC:     Bjorn Andersson <bjorn.andersson@linaro.org>,
        Ohad Ben-Cohen <ohad@wizery.com>,
        linux-remoteproc <linux-remoteproc@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        <linux-stm32@st-md-mailman.stormreply.com>,
        Julien Massot <julien.massot@iot.bzh>
References: <20210607173032.30133-1-arnaud.pouliquen@foss.st.com>
 <CANLsYkxAXiKTD=KB-45O+V7DAY4dbzd_Q3WdPoDrd=UdFqtw4w@mail.gmail.com>
From:   Arnaud POULIQUEN <arnaud.pouliquen@foss.st.com>
Message-ID: <3a554f3e-71c1-3073-038f-0a4f7cc2d94a@foss.st.com>
Date:   Tue, 8 Jun 2021 17:27:02 +0200
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Hi Mathieu,


On 6/8/21 4:26 PM, Mathieu Poirier wrote:
> Hi Arnaud,
> 
> Between remoteproc/RPMSG and CoreSight, I have 6 patchsets to review
> (including some of your work) before getting to this one.  As such it
> will take a little while.

No worries, i knew you have already some patchsets in your pipe.
As i used this series to test the rpmsg_ctrl [1], both were ready at the same time.
So i decided to push it because it can also help you to perform tests on the
series [1].

[1] https://patchwork.kernel.org/project/linux-remoteproc/list/?series=494021

Thanks,
Arnaud

> 
> Thanks,
> Mathieu
> 
> On Mon, 7 Jun 2021 at 11:30, Arnaud Pouliquen
> <arnaud.pouliquen@foss.st.com> wrote:
>>
>> Purpose:
>>   Allow the remote processor to instantiate a /dev/rpmsgX interface relying on the NS announcement
>>   of the "rpmsg-raw" service.
>>   This patchet is extracted from  the series [1] with rework to add rpmsg_create_default_ept helper.
>>
>>
>> Aim:
>>   There is no generic sysfs interface based on RPMsg that allows a user application to communicate
>>   with a remote processor in a simple way.
>>   The rpmsg_char dev solves a part of this problem by allowing an endpoint to be created on the
>>   local side. But it does not take advantage of the NS announcement mechanism implemented for some
>>   backends such as the virtio backend. So it is not possible to probe it from  a remote initiative.
>>   Extending the char rpmsg device to support NS announcement makes the rpmsg_char more generic.
>>   By announcing a "rpmg-raw" service, the firmware of a remote processor will be able to
>>   instantiate a /dev/rpmsgX interface providing to the user application a basic link to communicate
>>   with it without any knowledge of the rpmsg protocol.
>>
>> Implementation details:
>>   - Register a rpmsg driver for the rpmsg_char driver, associated to the "rpmsg-raw" channel service.
>>   - In case of rpmsg char device instantiated by the rpmsg bus (on NS announcement) manage the
>>     channel default endpoint to ensure a stable default endpoint address, for communication with
>>     the remote processor.
>>
>> How to test it:
>>   - This series can be applied on git/andersson/remoteproc.git for-next branch (dc0e14fa833b)
>>     + the "Restructure the rpmsg char to decorrelate the control part" series[2]
>>
>> [1] https://patchwork.kernel.org/project/linux-remoteproc/list/?series=475217
>> [2] https://patchwork.kernel.org/project/linux-remoteproc/list/?series=483793
>>
>>
>>
>> Arnaud Pouliquen (4):
>>   rpmsg: Introduce rpmsg_create_default_ept function
>>   rpmsg: char: Add possibility to create and reuse default endpoint
>>   rpmsg: char: Introduce the "rpmsg-raw" channel
>>   rpmsg: char: Return error if user tries to destroy a default endpoint.
>>
>>  drivers/rpmsg/rpmsg_char.c | 92 +++++++++++++++++++++++++++++++++++---
>>  drivers/rpmsg/rpmsg_core.c | 51 +++++++++++++++++++++
>>  include/linux/rpmsg.h      | 14 ++++++
>>  3 files changed, 151 insertions(+), 6 deletions(-)
>>
>> --
>> 2.17.1
>>