sfc: Workaround flush failures on Falcon B0

Under certain conditions a PHY may backpressure Falcon B0
in such a way that flushes timeout. In normal circumstances
the phy poller would fix the PHY, and the flush could complete.

But efx_nic_flush_queues() is always called after efx_stop_all(),
so the poller has been stopped. Even if this weren't the case,
how long would we have to wait for the poller to fix this? And
several callers of efx_nic_flush_queues() are about to reset
the device anyway - so we don't need to do anything.

Work around this bug by scheduling a reset. Ensure that the
MAC is never rewired back into the datapath before the reset
runs (we already ignore all rx events anyway).

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 3 deletions

diff --git a/drivers/net/sfc/falcon.c b/drivers/net/sfc/falcon.c
index 655b697b45b2..8558865ff380 100644
--- a/drivers/net/sfc/falcon.c
+++ b/drivers/net/sfc/falcon.c
@@ -548,7 +548,9 @@ void falcon_reconfigure_mac_wrapper(struct efx_nic *efx)
 {
         struct efx_link_state *link_state = &efx->link_state;
         efx_oword_t reg;
-        int link_speed;
+        int link_speed, isolate;
+
+        isolate = (efx->reset_pending != RESET_TYPE_NONE);
 
         switch (link_state->speed) {
         case 10000: link_speed = 3; break;
@@ -570,7 +572,7 @@ void falcon_reconfigure_mac_wrapper(struct efx_nic *efx)
          * discarded. */
         if (efx_nic_rev(efx) >= EFX_REV_FALCON_B0) {
                 EFX_SET_OWORD_FIELD(reg, FRF_BB_TXFIFO_DRAIN_EN,
-                                    !link_state->up);
+                                    !link_state->up || isolate);
         }
 
         efx_writeo(efx, &reg, FR_AB_MAC_CTRL);
@@ -584,7 +586,7 @@ void falcon_reconfigure_mac_wrapper(struct efx_nic *efx)
         EFX_SET_OWORD_FIELD(reg, FRF_AZ_RX_XOFF_MAC_EN, 1);
         /* Unisolate the MAC -> RX */
         if (efx_nic_rev(efx) >= EFX_REV_FALCON_B0)
-                EFX_SET_OWORD_FIELD(reg, FRF_BZ_RX_INGR_EN, 1);
+                EFX_SET_OWORD_FIELD(reg, FRF_BZ_RX_INGR_EN, !isolate);
         efx_writeo(efx, &reg, FR_AZ_RX_CFG);
 }