On 6/2/2026 3:34 AM, Arnaud POULIQUEN wrote:
>
>
> 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 <[email protected]>
>> ---
>>
>> 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
>
Here, I just want to demonstrate rpmsg_get_mtu() API. Now we can have a
configurable size of the RPMsg buffer. So rpmsg_get_mtu() API can be
used to check correct buffer length before even using rpmsg_send() API.
I think I should check msg length against mtu size as well.
> Regards,
> Arnaud
>
>> /* send a message to our remote processor */
>> ret = rpmsg_send(rpdev->ept, MSG, strlen(MSG));
>> if (ret) {
>
