Hi Adam,

On Thu, Sep 04, 2025 at 12:05:42AM -0400, Adam Young wrote:

Implementation of network driver for
Management Control Transport Protocol(MCTP)
over Platform Communication Channel(PCC)

DMTF DSP:0292
https://www.dmtf.org/sites/default/files/standards/documents/\
DSP0292_1.0.0WIP50.pdf

MCTP devices are specified via ACPI by entries
in DSDT/SDST and reference channels specified
in the PCCT.  Messages are sent on a type 3 and
received on a type 4 channel.  Communication with
other devices use the PCC based doorbell mechanism;
a shared memory segment with a corresponding
interrupt and a memory register used to trigger
remote interrupts.

This driver takes advantage of PCC mailbox buffer
management. The data section of the struct sk_buff
that contains the outgoing packet is sent to the mailbox,
already properly formatted  as a PCC message.  The driver
is also responsible for allocating a struct sk_buff that
is then passed to the mailbox and used to record the
data in the shared buffer. It maintains a list of both
outging and incoming sk_buffs to match the data buffers

If the mailbox ring buffer is full, the driver stops the
incoming packet queues until a message has been sent,
freeing space in the ring buffer.

When the Type 3 channel outbox receives a txdone response
interrupt, it consumes the outgoing sk_buff, allowing
it to be freed.

Sorry for not reviewing your mailbox changes in time, but I have
comments/concerns on the changes merged. I will respond on the original
thread with questions if I manage to find it, but it doesn't look good
at all to me. So I would want these changes to be on hold(not to be
merged at all).

-- 
Regards,
Sudeep