netdev - Re: [PATCH v2 0/3] MCTP over PCC

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Date: Wed, 19 Jun 2024 23:10:18 -0400
From: Adam Young <admiyo@...eremail.onmicrosoft.com>
To: admiyo@...amperecomputing.com
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/3] MCTP over PCC

Apologies.  I just saw that there was more feedback on the previous 
patchset.  I am addressing that now.

On 6/19/24 16:05, admiyo@...amperecomputing.com wrote:
> From: Adam Young <admiyo@...amperecomputing.com>
>
> This series adds support for the Management Control Transport Protocol (MCTP)
> over the Platform Communication Channel (PCC) mechanism.
>
> MCTP defines a communication model intended to
> facilitate communication between Management controllers
> and other management controllers, and between Management
> controllers and management devices
>
> PCC is a mechanism for communication between components within
> the  Platform.  It is a composed of shared memory regions,
> interrupt registers, and status registers.
>
> The MCTP over PCC driver makes use of two PCC channels. For
> sending messages, it uses a Type 3 channel, and for receiving
> messages it uses the paired Type 4 channel.  The device
> and corresponding channels are specified via ACPI.
>
> The first patch in the series implements a mechanism to allow the driver
> to indicate whether an ACK should be sent back to the caller
> after processing the interrupt.  This is an optional feature in
> the PCC code, but has been made explicitly required in another driver.
> The implementation here maintains the backwards compatibility of that
> driver.
>
> The second patch in the series is the required change from ACPICA
> code that will be imported into the Linux kernel when synchronized
> with the ACPICA repository. It ahs already merged there and will
> be merged in as is.  It is included here so that the patch series
> can run and be tested prior to that merge.
>
> Changes in V3
> - removed unused header
> - removed spurious space
> - removed spurious semis after functiomns
> - removed null assignment for init
> - remove redundant set of device on skb
> - tabify constant declarations
> - added  rtnl_link_stats64 function
> - set MTU to minimum to start
> - clean up logic on driver removal
> - remove cast on void * assignment
> - call cleanup function directly
> - check received length before allocating skb
> - introduce symbolic constatn for ACK FLAG MASK
> - symbolic constant for PCC header flag.
> - Add namespace ID to PCC magic
> - replaced readls with copy from io of PCC header
>
> Changes in V2
>
> - All Variable Declarations are in reverse Xmass Tree Format
> - All Checkpatch Warnings Are Fixed
> - Removed Dead code
> - Added packet tx/rx stats
> - Removed network physical address.  This is still in
>    disucssion in the spec, and will be added once there
>    is consensus. The protocol can be used with out it.
>    This also lead to the removal of the Big Endian
>    conversions.
> - Avoided using non volatile pointers in copy to and from io space
> - Reorderd the patches to put the ACK check for the PCC Mailbox
>    as a pre-requisite.  The corresponding change for the MCTP
>    driver has been inlined in the main patch.
> - Replaced magic numbers with constants, fixed typos, and other
>    minor changes from code review.
>
> Code Review Change not made
>
> - Did not change the module init unload function to use the
>    ACPI equivalent as they do not remove all devices prior
>    to unload, leading to dangling references and seg faults.
>
> Adam Young (3):
>    mctp pcc: Check before sending MCTP PCC response ACK
>    mctp pcc: Allow PCC Data Type in MCTP resource.
>    mctp pcc: Implement MCTP over PCC Transport
>
>   drivers/acpi/acpica/rsaddr.c |   2 +-
>   drivers/mailbox/pcc.c        |   5 +-
>   drivers/net/mctp/Kconfig     |  13 ++
>   drivers/net/mctp/Makefile    |   1 +
>   drivers/net/mctp/mctp-pcc.c  | 373 +++++++++++++++++++++++++++++++++++
>   include/acpi/pcc.h           |   1 +
>   6 files changed, 393 insertions(+), 2 deletions(-)
>   create mode 100644 drivers/net/mctp/mctp-pcc.c
>