sfc: Disable TX descriptor prefetch watchdog

This hardware watchdog can misfire, so it does more harm than good.
Signed-off-by: NBen Hutchings <bhutchings@solarflare.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/sfc/nic.c

@@ -1576,6 +1576,8 @@ void efx_nic_init_common(struct efx_nic *efx)
 	EFX_SET_OWORD_FIELD(temp, FRF_AZ_TX_SOFT_EVT_EN, 1);
 	/* Prefetch threshold 2 => fetch when descriptor cache half empty */
 	EFX_SET_OWORD_FIELD(temp, FRF_AZ_TX_PREF_THRESHOLD, 2);
+	/* Disable hardware watchdog which can misfire */
+	EFX_SET_OWORD_FIELD(temp, FRF_AZ_TX_PREF_WD_TMR, 0x3fffff);
 	/* Squash TX of packets of 16 bytes or less */
 	if (efx_nic_rev(efx) >= EFX_REV_FALCON_B0)
 		EFX_SET_OWORD_FIELD(temp, FRF_BZ_TX_FLUSH_MIN_LEN_EN, 1);