Re: [PATCH v9 00/11] Restructure the rpmsg_char driver and introduce rpmsg_ctrl driver

[Philipp Rossak <embed3d@gmail.com>]

Hi Arnaud,

thanks for working on this! I'm currently testing/using this patch 
series on my imx7d project because it adds the capability that the 
remote processor can register it's endpoints dynamically (as mentioned 
in the objectives).

After a few tests, debugging, and checking the openamp specification [1] 
I think that you missed the second ns_announcement that should be sent 
from linux master to the slave after it created the channel/endpoint. 
Without this second announcement the remote processor is not able to 
send messages to the linux master because it doesn't know the 
destination address until it receives a message from the linux master.

Cheers,
Philipp


[1]: 
https://github.com/OpenAMP/open-amp/blob/main/docs/img/coprocessor-rpmsg-ns.png

On 24.01.22 11:25, Arnaud Pouliquen wrote:
> Updates from V8 [1]:
> - rebase on 5.17-rc1 + rpmsg char cdev release fixes[2][3]
> - updates based on Bjorn Andersson's comments:
>    - remove rpmsg_create_default_ept API, set directly the ept->priv in rpmsg_chrdev_probe
>      function.
>    - rework commit message in [8/9]rpmsg: char: Introduce the "rpmsg-raw" channel
> 
> Patchset description:
> 
> The current rpmsg_char module implements a /dev/rpmsg_ctrl interface that provides the ability to
> instantiate char devices (/dev/rpmsgX) associated with an rpmsg endpoint for communication with the
> remote processor.
> This implementation fits with QCOM rpmsg backend but not with the magement by chanel implemented
> in the generic rpmsg virtio backend.
> This series restructures the rpmsg_char driver to decorrelate the control part from the data part
> in order to improve its compatible with the rpmsg virtio backend.
> 
> Objective:
> - Expose a /dev/rpmsg_ctrlX interface for the application that is no longer dedicated to the
>    rpmsg_char but generalized to all rpmsg services. This offers capability to create and destroy
>    rpmsg channels from a user's application initiative (using the new RPMSG_CREATE_DEV_IOCTL and
>    RPMSG_DESTROY_DEV_IOCTL controls).
>    An application will be able to create/establish an rpmsg communication channel to communicate
>    with the remote processor, and not only wait the remote processor initiative.
>    This is interesting for example to establish a temporary communication link for diagnosis,
>    calibration, debugging... or instantiate  new data flows on some user actions.
> - Add capability to probe the rpmsg_char device at the initiative of the remote processor
>   (rpmsg service announcement mechanism).
>    This allows platforms based on the rpmsg virtio backend to create the /dev/rpmgX interface with
>    a rpmsg name service announcement.
> 
> Subsets:
>    - Extract the control part of the char dev and create the rpmsg_ctrl.c file (patches 1 to 6)
>    - Introduce the "rpmsg-raw" channel in rpmsg_char(patches 7 to 10)
>    - Introduce the RPMSG_CREATE_DEV_IOCTL IOCTL and RPMSG_DESTROY_DEV_IOCTL to instantiate RPMsg
>      devices (patch 11)
>      The application can then create or release a channel by specifying:
>         - the name service of the device to instantiate.
>         - the source address.
>         - the destination address.
> 
> This series has be applied and tested on 'commit e783362eb54c ("Linux 5.17-rc1") +
> rpmsg_char cdev release fixes [2][3]
> 
> [1] https://lkml.org/lkml/2021/12/7/186
> [2] https://lkml.org/lkml/2022/1/10/1129
> [3] https://lkml.org/lkml/2022/1/10/1130
> 
> Arnaud Pouliquen (11):
>    rpmsg: char: Export eptdev create and destroy functions
>    rpmsg: Create the rpmsg class in core instead of in rpmsg char
>    rpmsg: Move the rpmsg control device from rpmsg_char to rpmsg_ctrl
>    arm: configs: Configs that had RPMSG_CHAR now get RPMSG_CTRL
>    RISC-V: configs: Configs that had RPMSG_CHAR now get RPMSG_CTRL
>    arm64: defconfig: Config that had RPMSG_CHAR now gets RPMSG_CTRL
>    rpmsg: Update rpmsg_chrdev_register_device function
>    rpmsg: char: Refactor rpmsg_chrdev_eptdev_create function
>    rpmsg: char: Add possibility to use default endpoint of the rpmsg
>      device
>    rpmsg: char: Introduce the "rpmsg-raw" channel
>    rpmsg: ctrl: Introduce new RPMSG_CREATE/RELEASE_DEV_IOCTL controls
> 
>   arch/arm/configs/qcom_defconfig   |   1 +
>   arch/arm64/configs/defconfig      |   1 +
>   arch/riscv/configs/defconfig      |   1 +
>   arch/riscv/configs/rv32_defconfig |   1 +
>   drivers/rpmsg/Kconfig             |   8 +
>   drivers/rpmsg/Makefile            |   1 +
>   drivers/rpmsg/qcom_glink_native.c |   2 +-
>   drivers/rpmsg/qcom_smd.c          |   2 +-
>   drivers/rpmsg/rpmsg_char.c        | 231 +++++++++++-----------------
>   drivers/rpmsg/rpmsg_char.h        |  46 ++++++
>   drivers/rpmsg/rpmsg_core.c        |  15 +-
>   drivers/rpmsg/rpmsg_ctrl.c        | 243 ++++++++++++++++++++++++++++++
>   drivers/rpmsg/rpmsg_internal.h    |  10 +-
>   drivers/rpmsg/virtio_rpmsg_bus.c  |   2 +-
>   include/uapi/linux/rpmsg.h        |  10 ++
>   15 files changed, 419 insertions(+), 155 deletions(-)
>   create mode 100644 drivers/rpmsg/rpmsg_char.h
>   create mode 100644 drivers/rpmsg/rpmsg_ctrl.c
>