[PATCH net v2 0/1] net: stmmac: Track the TX DMA threshold per queue

[Ovidiu Panait]

On the Renesas RZ/V2H platform, which has two dwmac4 controllers, we
observed sporadic iperf3 TCP TX failures on one of the controllers, with
throughput dropping from >900Mbit/s to ~1Mbit/s due to TX underflows and
the resulting retransmissions.

Commit 3a6c12a0c6c3 ("net: stmmac: bump tc when get underflow error from
DMA descriptor") made dwmac4 raise the DMA threshold of the queues that
report TX underflows, by increasing a global module parameter 'tc'.
However, this logic does not work correctly across multiple queues and
controllers, and can leave the TX DMA threshold stuck at 64 bytes.

This series fixes that logic to track the TX DMA threshold per queue for
each controller.

v2:
- Dropped patch 2/2, as it is not suitable for net. It will be sent for
  net-next at a later time.
- Added "Reviewed-by" tag from Maxime.

v1: https://lore.kernel.org/all/20261013114503.57487-1-ovidiu.panait.rb@xxxxxxxxxxx/

Ovidiu Panait (1):
  net: stmmac: Track the TX DMA threshold per queue

 drivers/net/ethernet/stmicro/stmmac/stmmac.h  |  1 +
 .../net/ethernet/stmicro/stmmac/stmmac_main.c | 33 +++++++++++--------
 2 files changed, 21 insertions(+), 13 deletions(-)

-- 
2.34.1