From 1029c89bafc714c1b987f29e3bc124a7b63d28d5 Mon Sep 17 00:00:00 2001 From: Tanmay Shah Date: Fri, 28 Aug 2026 07:58:52 -0700 Subject: [PATCH] samples: rpmsg: Add MTU size info 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 Acked-by: Arnaud Pouliquen Link: https://lore.kernel.org/r/20260828145853.2843486-6-tanmay.shah@amd.com Signed-off-by: Mathieu Poirier --- samples/rpmsg/rpmsg_client_sample.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) diff --git a/samples/rpmsg/rpmsg_client_sample.c b/samples/rpmsg/rpmsg_client_sample.c index ae5081662283..4c43436aadb6 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, msg_len; dev_info(&rpdev->dev, "new channel: 0x%x -> 0x%x!\n", rpdev->src, rpdev->dst); @@ -62,8 +63,25 @@ 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); + + msg_len = strlen(MSG); + /* make sure our message fits in a single rpmsg buffer */ + if (msg_len > mtu) { + dev_err(&rpdev->dev, + "message size %zu exceeds rpmsg MTU size %ld\n", + strlen(MSG), mtu); + return -EMSGSIZE; + } + /* send a message to our remote processor */ - ret = rpmsg_send(rpdev->ept, MSG, strlen(MSG)); + ret = rpmsg_send(rpdev->ept, MSG, msg_len); if (ret) { dev_err(&rpdev->dev, "rpmsg_send failed: %d\n", ret); return ret;