On Fri, Oct 13, 2023 at 12:06:25PM +0800, Matt Johnston wrote:

Provides MCTP network transport over an I3C bus, as specified in
DMTF DSP0233.

Each I3C bus (with "mctp-controller" devicetree property) gets an
"mctpi3cX" net device created. I3C devices are reachable as remote
endpoints through that net device. Link layer addressing uses the
I3C PID as a fixed hardware address for neighbour table entries.

The driver matches I3C devices that have the MIPI assigned DCR 0xCC for
MCTP.

Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>

Hi Matt,

one minor nit below, which you can take, leave, or leave for later
as far as I am concerned.

Overall the patch looks good to me and I see that Paolo's review of v5 has
has been addressed.

Reviewed-by: Simon Horman <horms@kernel.org>

+/* List of mctp_i3c_busdev */
+static LIST_HEAD(busdevs);
+/* Protects busdevs, as well as mctp_i3c_bus.devs lists */
+static DEFINE_MUTEX(busdevs_lock);
+
+struct mctp_i3c_bus {
+	struct net_device *ndev;
+
+	struct task_struct *tx_thread;
+	wait_queue_head_t tx_wq;
+	/* tx_lock protects tx_skb and devs */
+	spinlock_t tx_lock;
+	/* Next skb to transmit */
+	struct sk_buff *tx_skb;
+	/* Scratch buffer for xmit */
+	u8 tx_scratch[MCTP_I3C_MAXBUF];
+
+	/* Element of busdevs */
+	struct list_head list;

I am unsure if it is important, but I observe that on x86_64
list spans a cacheline.

+
+	/* Provisioned ID of our controller */
+	u64 pid;
+
+	struct i3c_bus *bus;
+	/* Head of mctp_i3c_device.list. Protected by busdevs_lock */
+	struct list_head devs;
+};

...