Re: [PATCH 0/8] net: mrmac: Fix Rx packet loss on back-to-back frames

[Michal Simek <michal.simek@amd.com>]

On 8/20/26 11:25, Padmarao Begari wrote:
> The MRMAC Rx path drops frames when two arrive back to back. recv()
> always starts at rx_bd[0] and clears the status of both descriptors,
> and the status field is the only record that a frame arrived, so the
> second frame is lost without any error being reported. This shows up
> with multiple boards on a switch, where the extra traffic makes
> back-to-back arrivals common and network transfers time out.
> 
> Fixing that needs an Rx ring the driver can index, so the series first
> makes the ring scalable and then fixes the bug:
> 
>    1-3  Independent cleanups: check memalign() failures, give the
>         driver its own Rx buffer pool instead of borrowing the shared
>         net_rx_packets[], and read the link speed from the standard
>         max-speed property.
> 
>    4-6  Make the descriptor ring scale: index the contiguous BD blocks
>         directly, build the Rx chain in a loop over RX_DESC, and
>         program CURDESC only once the ring is complete in memory.
> 
>    7    Track the descriptor to consume next in rx_bd_idx and take
>         completion from the per-descriptor COMPLETE bit, so a
>         descriptor goes back to hardware only after the network stack
>         has read it.
> 
>    8    Size the Rx ring from ETH_PACKETS_BATCH_RECV, so a full
>         eth_rx() call can be served without hardware running out of
>         descriptors.
> 
> Padmarao Begari (8):
>    net: mrmac: check memalign() return values
>    net: mrmac: use a driver-owned RX buffer pool
>    net: mrmac: switch to max-speed property
>    net: mrmac: use contiguous BD arrays
>    net: mrmac: initialize the Rx BD ring in a loop
>    net: mrmac: write CURDESC after ring setup
>    net: mrmac: fix Rx packet loss on back-to-back frames
>    net: mrmac: increase the Rx BD ring
> 
>   drivers/net/xilinx_axi_mrmac.c | 235 +++++++++++++++++----------------
>   drivers/net/xilinx_axi_mrmac.h |  20 ++-
>   2 files changed, 137 insertions(+), 118 deletions(-)
> 

Applied.
M