diff options
Diffstat (limited to 'drivers/net/ethernet/qualcomm/emac/emac-mac.c')
| -rw-r--r-- | drivers/net/ethernet/qualcomm/emac/emac-mac.c | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/drivers/net/ethernet/qualcomm/emac/emac-mac.c b/drivers/net/ethernet/qualcomm/emac/emac-mac.c index bcd4708b3745..0ea3ca09c689 100644 --- a/drivers/net/ethernet/qualcomm/emac/emac-mac.c +++ b/drivers/net/ethernet/qualcomm/emac/emac-mac.c @@ -551,6 +551,28 @@ static void emac_mac_start(struct emac_adapter *adpt) mac &= ~(HUGEN | VLAN_STRIP | TPAUSE | SIMR | HUGE | MULTI_ALL | DEBUG_MODE | SINGLE_PAUSE_MODE); + /* Enable single-pause-frame mode if requested. + * + * If enabled, the EMAC will send a single pause frame when the RX + * queue is full. This normally leads to packet loss because + * the pause frame disables the remote MAC only for 33ms (the quanta), + * and then the remote MAC continues sending packets even though + * the RX queue is still full. + * + * If disabled, the EMAC sends a pause frame every 31ms until the RX + * queue is no longer full. Normally, this is the preferred + * method of operation. However, when the system is hung (e.g. + * cores are halted), the EMAC interrupt handler is never called + * and so the RX queue fills up quickly and stays full. The resuling + * non-stop "flood" of pause frames sometimes has the effect of + * disabling nearby switches. In some cases, other nearby switches + * are also affected, shutting down the entire network. + * + * The user can enable or disable single-pause-frame mode + * via ethtool. + */ + mac |= adpt->single_pause_mode ? SINGLE_PAUSE_MODE : 0; + writel_relaxed(csr1, adpt->csr + EMAC_EMAC_WRAPPER_CSR1); writel_relaxed(mac, adpt->base + EMAC_MAC_CTRL); |