Re: [PATCH v3 4/4] samples: rpmsg: add MTU size info

[Arnaud POULIQUEN <arnaud.pouliquen@foss.st.com>]

On 5/29/26 18:43, Tanmay Shah wrote:
> RPMsg MTU size can be variable now and no longer hardcoded to 512 bytes.
> Add log to the sample driver that prints current MTU size of the rpmsg
> buffer.
> 
> Signed-off-by: Tanmay Shah <tanmay.shah@amd.com>
> ---
> 
> Changes in v3:
>    - Check for error when retrieving MTU size
>    - %s/mtu/MTU/
> 
>   samples/rpmsg/rpmsg_client_sample.c | 9 +++++++++
>   1 file changed, 9 insertions(+)
> 
> diff --git a/samples/rpmsg/rpmsg_client_sample.c b/samples/rpmsg/rpmsg_client_sample.c
> index ae5081662283..55afa53189af 100644
> --- a/samples/rpmsg/rpmsg_client_sample.c
> +++ b/samples/rpmsg/rpmsg_client_sample.c
> @@ -52,6 +52,7 @@ static int rpmsg_sample_probe(struct rpmsg_device *rpdev)
>   {
>   	int ret;
>   	struct instance_data *idata;
> +	ssize_t mtu;
>   
>   	dev_info(&rpdev->dev, "new channel: 0x%x -> 0x%x!\n",
>   					rpdev->src, rpdev->dst);
> @@ -62,6 +63,14 @@ static int rpmsg_sample_probe(struct rpmsg_device *rpdev)
>   
>   	dev_set_drvdata(&rpdev->dev, idata);
>   
> +	mtu = rpmsg_get_mtu(rpdev->ept);
> +	if (mtu < 0) {
> +		dev_warn(&rpdev->dev, "invalid rpmsg MTU size = %ld\n", mtu);
> +		return mtu;
> +	}
> +
> +	dev_info(&rpdev->dev, "rpmsg MTU size = %ld\n", mtu);
> +

Do you really need this commit? rpmsg_send should return an error if the 
buffer size is insufficient [1].

[1] 
https://elixir.bootlin.com/linux/v7.0.10/source/drivers/rpmsg/virtio_rpmsg_bus.c#L517

Regards,
Arnaud

>   	/* send a message to our remote processor */
>   	ret = rpmsg_send(rpdev->ept, MSG, strlen(MSG));
>   	if (ret) {