Re: [PATCH] rpmsg_ns: Work around TI non-standard message

[Mathieu Poirier <mathieu.poirier@linaro.org>]

Good morning Richard,

On Fri, Oct 11, 2024 at 02:39:22PM +0200, Richard Weinberger wrote:
> Texas Instruments ships a patch in their vendor kernels,
> which adds a new NS message that includes a description field.
> While TI is free to do whatever they want in their copy of the kernel,
> it becomes a mess when people switch to a mainline kernel and want
> to use their existing DSP programs with it.

I suspect there is a lot more things to change when going from downstream to a
mainline kernel.  

> 
> To make it easier to migrate to a mainline kernel,
> let's make the kernel aware of their non-standard extension but
> briefly ignore the description field.

In my opinion the real fix here is to get TI to use the standard message
announcement structure.  The ->desc field doesn't seem to be that useful since
it gets discarted.

Thanks,
Mathieu

> 
> [0] https://patchwork.kernel.org/project/linux-remoteproc/patch/20190815231448.10100-1-s-anna@ti.com/
> [1] https://stash.phytec.com/projects/PUB/repos/linux-phytec-ti/commits/aeded1f439effc84aa9f4e341a6e92ce1844ab98#drivers/rpmsg/virtio_rpmsg_bus.c
> 
> Cc: ohad@wizery.com
> Cc: s-anna@ti.com
> Cc: t-kristo@ti.com
> Signed-off-by: Richard Weinberger <richard@nod.at>
> ---
> FWIW, this is a forward port of a patch I'm using on v6.6.
> 
> Thanks,
> //richard
> ---
>  drivers/rpmsg/rpmsg_ns.c | 30 ++++++++++++++++++++++--------
>  include/linux/rpmsg/ns.h |  8 ++++++++
>  2 files changed, 30 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/rpmsg/rpmsg_ns.c b/drivers/rpmsg/rpmsg_ns.c
> index bde8c8d433e0a..2fb3721eb0141 100644
> --- a/drivers/rpmsg/rpmsg_ns.c
> +++ b/drivers/rpmsg/rpmsg_ns.c
> @@ -31,10 +31,11 @@ EXPORT_SYMBOL(rpmsg_ns_register_device);
>  static int rpmsg_ns_cb(struct rpmsg_device *rpdev, void *data, int len,
>  		       void *priv, u32 src)
>  {
> -	struct rpmsg_ns_msg *msg = data;
>  	struct rpmsg_device *newch;
>  	struct rpmsg_channel_info chinfo;
>  	struct device *dev = rpdev->dev.parent;
> +	__rpmsg32 ns_addr, ns_flags;
> +	char *ns_name;
>  	int ret;
>  
>  #if defined(CONFIG_DYNAMIC_DEBUG)
> @@ -42,23 +43,36 @@ static int rpmsg_ns_cb(struct rpmsg_device *rpdev, void *data, int len,
>  			 data, len, true);
>  #endif
>  
> -	if (len != sizeof(*msg)) {
> +	if (len == sizeof(struct rpmsg_ns_msg)) {
> +		struct rpmsg_ns_msg *msg = data;
> +
> +		ns_addr = msg->addr;
> +		ns_flags = msg->flags;
> +		ns_name = msg->name;
> +	} else if (len == sizeof(struct __rpmsg_ns_msg_ti)) {
> +		struct __rpmsg_ns_msg_ti *msg = data;
> +
> +		ns_addr = msg->addr;
> +		ns_flags = msg->flags;
> +		ns_name = msg->name;
> +		dev_warn(dev, "non-standard ns msg found\n");
> +	} else {
>  		dev_err(dev, "malformed ns msg (%d)\n", len);
>  		return -EINVAL;
>  	}
>  
>  	/* don't trust the remote processor for null terminating the name */
> -	msg->name[RPMSG_NAME_SIZE - 1] = '\0';
> +	ns_name[RPMSG_NAME_SIZE - 1] = '\0';
>  
> -	strscpy_pad(chinfo.name, msg->name, sizeof(chinfo.name));
> +	strscpy_pad(chinfo.name, ns_name, sizeof(chinfo.name));
>  	chinfo.src = RPMSG_ADDR_ANY;
> -	chinfo.dst = rpmsg32_to_cpu(rpdev, msg->addr);
> +	chinfo.dst = rpmsg32_to_cpu(rpdev, ns_addr);
>  
>  	dev_info(dev, "%sing channel %s addr 0x%x\n",
> -		 rpmsg32_to_cpu(rpdev, msg->flags) & RPMSG_NS_DESTROY ?
> -		 "destroy" : "creat", msg->name, chinfo.dst);
> +		 rpmsg32_to_cpu(rpdev, ns_flags) & RPMSG_NS_DESTROY ?
> +		 "destroy" : "creat", ns_name, chinfo.dst);
>  
> -	if (rpmsg32_to_cpu(rpdev, msg->flags) & RPMSG_NS_DESTROY) {
> +	if (rpmsg32_to_cpu(rpdev, ns_flags) & RPMSG_NS_DESTROY) {
>  		ret = rpmsg_release_channel(rpdev, &chinfo);
>  		if (ret)
>  			dev_err(dev, "rpmsg_destroy_channel failed: %d\n", ret);
> diff --git a/include/linux/rpmsg/ns.h b/include/linux/rpmsg/ns.h
> index a7804edd6d58f..60fca84ad4cea 100644
> --- a/include/linux/rpmsg/ns.h
> +++ b/include/linux/rpmsg/ns.h
> @@ -26,6 +26,14 @@ struct rpmsg_ns_msg {
>  	__rpmsg32 flags;
>  } __packed;
>  
> +/* Non-standard extended ns message by Texas Instruments */
> +struct __rpmsg_ns_msg_ti {
> +	char name[RPMSG_NAME_SIZE];
> +	char desc[RPMSG_NAME_SIZE]; /* ignored */
> +	u32 addr;
> +	u32 flags;
> +} __packed;
> +
>  /**
>   * enum rpmsg_ns_flags - dynamic name service announcement flags
>   *
> -- 
> 2.35.3
>