[PATCH net 0/2] net: enetc: restore RX ring congestion mode after ring reconfiguration

[wei . fang]

From: Wei Fang <wei.fang@xxxxxxx>

The RX BD ring congestion mode (CM) enables the ENETC MAC to generate
PAUSE frames when ingress congestion occurs. It is configured only in
the phylink .mac_link_up() callback, which is invoked when the link
status changes.

However, enetc_reconfigure() tears down and re-creates the RX BD rings
at runtime without any link status change, for example when enabling or
disabling PTP RX hardware timestamping. enetc_setup_rxbdr() rebuilds the
RBMR register from zero, which clears the CM bit, and since the link
status does not change, .mac_link_up() is not called again to restore
it. As a result, flow control silently stops working after such a
reconfiguration.

To solve this issue, track the desired CM state in a software flag
ENETC_RXBDR_CM, which is maintained by the .mac_link_up() /
.mac_link_down() callbacks and consulted by enetc_setup_rxbdr() when the
RX BD rings are (re)configured. Both ENETC v1 and ENETC v4 are affected
and are fixed in the same way.

Wei Fang (2):
  net: enetc: restore RX ring congestion mode after ring reconfiguration
  net: enetc: restore RX ring congestion mode for ENETC v4

 drivers/net/ethernet/freescale/enetc/enetc.c     | 4 ++++
 drivers/net/ethernet/freescale/enetc/enetc.h     | 1 +
 drivers/net/ethernet/freescale/enetc/enetc4_pf.c | 8 ++++++++
 drivers/net/ethernet/freescale/enetc/enetc_pf.c  | 5 +++++
 4 files changed, 18 insertions(+)

-- 
2.34.1