linux-kernel - Re: [PATCH v6 03/10] rpmsg: Move the rpmsg control device from rpmsg_char to rpmsg

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Date:   Mon, 1 Nov 2021 12:07:34 -0500
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Arnaud Pouliquen <arnaud.pouliquen@...s.st.com>
Cc:     Ohad Ben-Cohen <ohad@...ery.com>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com, julien.massot@....bzh
Subject: Re: [PATCH v6 03/10] rpmsg: Move the rpmsg control device from
 rpmsg_char to rpmsg_ctrl

On Fri 22 Oct 07:54 CDT 2021, Arnaud Pouliquen wrote:

> Create the rpmsg_ctrl.c module and move the code related to the
> rpmsg_ctrldev device in this new module.
> 
> Add the dependency between rpmsg_char and rpmsg_ctrl in the
> kconfig file.
> 
> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@...s.st.com>
> Reviewed-by: Mathieu Poirier <mathieu.poirier@...aro.org>
> 
> ---
> update vs previous version:
> - set the ctrl device class with new rpmsg_get_class API for legacy support
> ---
>  drivers/rpmsg/Kconfig      |   9 ++
>  drivers/rpmsg/Makefile     |   1 +
>  drivers/rpmsg/rpmsg_char.c | 169 +----------------------------
>  drivers/rpmsg/rpmsg_char.h |   2 +
>  drivers/rpmsg/rpmsg_ctrl.c | 216 +++++++++++++++++++++++++++++++++++++
>  5 files changed, 230 insertions(+), 167 deletions(-)
>  create mode 100644 drivers/rpmsg/rpmsg_ctrl.c
> 
> diff --git a/drivers/rpmsg/Kconfig b/drivers/rpmsg/Kconfig
> index 0b4407abdf13..d822ec9ec692 100644
> --- a/drivers/rpmsg/Kconfig
> +++ b/drivers/rpmsg/Kconfig
> @@ -10,11 +10,20 @@ config RPMSG_CHAR
>  	tristate "RPMSG device interface"
>  	depends on RPMSG
>  	depends on NET
> +	select RPMSG_CTRL

We don't want select of user selectable config options.

>  	help
>  	  Say Y here to export rpmsg endpoints as device files, usually found
>  	  in /dev. They make it possible for user-space programs to send and
>  	  receive rpmsg packets.
>  
> +config RPMSG_CTRL

I still don't like the introduction of more Kconfig options - search the
list for the number of patches that has corrected Kconfig dependency
issues.

That said, if you get it right...

> +	tristate "RPMSG control interface"
> +	depends on RPMSG
> +	help
> +	  Say Y here to enable the support of the /dev/rpmsg_ctrlX API. This API
> +	  allows user-space programs to create endpoints with specific service name,
> +	  source and destination addresses.
> +
>  config RPMSG_NS
>  	tristate "RPMSG name service announcement"
>  	depends on RPMSG
[..]
> diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
[..]
> diff --git a/drivers/rpmsg/rpmsg_char.h b/drivers/rpmsg/rpmsg_char.h
> index 109c2c43005f..ff1acc42628a 100644
> --- a/drivers/rpmsg/rpmsg_char.h
> +++ b/drivers/rpmsg/rpmsg_char.h
> @@ -12,6 +12,8 @@
>   * In such case a kernel warning is printed to help develloper to fix the issue.
>   */
>  
> +#define RPMSG_DEV_MAX	(MINORMASK + 1)

This was used to define the minors of the rpmsg chdev, now you're
splitting that range in one for the ctrl and one for the char.

Moving this define to a common place gives an impression that there's a
relationship between the two, but I don't see any. So I think you should
duplicate this in the two files - just like the other stuff.

> +
>  #if IS_REACHABLE(CONFIG_RPMSG_CHAR)
>  /**
>   * rpmsg_chrdev_eptdev_create() - register char device based on an endpoint
> diff --git a/drivers/rpmsg/rpmsg_ctrl.c b/drivers/rpmsg/rpmsg_ctrl.c
> new file mode 100644
> index 000000000000..1d3c12e5cdcf
> --- /dev/null
> +++ b/drivers/rpmsg/rpmsg_ctrl.c
> @@ -0,0 +1,216 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2021, STMicroelectronics

Did you actually change anything that warrant the explicit copyright
claim?

> + * Copyright (c) 2016, Linaro Ltd.
> + * Copyright (c) 2012, Michal Simek <monstr@...str.eu>
> + * Copyright (c) 2012, PetaLogix
> + * Copyright (c) 2011, Texas Instruments, Inc.
> + * Copyright (c) 2011, Google, Inc.
> + *
> + * Based on rpmsg performance statistics driver by Michal Simek, which in turn
> + * was based on TI & Google OMX rpmsg driver.
> + */
[..]
> +static int rpmsg_ctrldev_probe(struct rpmsg_device *rpdev)
> +{
> +	struct rpmsg_ctrldev *ctrldev;
> +	struct device *dev;
> +	int ret;
> +
> +	ctrldev = kzalloc(sizeof(*ctrldev), GFP_KERNEL);
> +	if (!ctrldev)
> +		return -ENOMEM;
> +
> +	ctrldev->rpdev = rpdev;
> +
> +	dev = &ctrldev->dev;
> +	device_initialize(dev);
> +	dev->parent = &rpdev->dev;
> +	dev->class = rpmsg_get_class();

Thank you.

Regards,
Bjorn