igc: remove I226 Qbv BaseTime restriction

Remove the Qbv BaseTime restriction for I226 so that the BaseTime can be
scheduled to the future time. A new register bit of Tx Qav Control
(Bit-7: FutScdDis) was introduced to allow I226 scheduling future time as
Qbv BaseTime and not having the Tx hang timeout issue.

Besides, according to datasheet section 7.5.2.9.3.3, FutScdDis bit has to
be configured first before the cycle time and base time.

Indeed the FutScdDis bit is only active on re-configuration, thus we have
to set the BASET_L to zero and then only set it to the desired value.

Please also note that the Qbv configuration flow is moved around based on
the Qbv programming guideline that is documented in the latest datasheet.

Co-developed-by: Tan Tee Min <tee.min.tan@linux.intel.com>
Signed-off-by: Tan Tee Min <tee.min.tan@linux.intel.com>
Signed-off-by: Muhammad Husaini Zulkifli <muhammad.husaini.zulkifli@intel.com>
Tested-by: Naama Meir <naamax.meir@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

1 files changed, 29 insertions, 15 deletions

diff --git a/drivers/net/ethernet/intel/igc/igc_tsn.c b/drivers/net/ethernet/intel/igc/igc_tsn.c
index bb10d7b65232..28325dc4fc5b 100644
--- a/drivers/net/ethernet/intel/igc/igc_tsn.c
+++ b/drivers/net/ethernet/intel/igc/igc_tsn.c
@@ -2,6 +2,7 @@
 /* Copyright (c)  2019 Intel Corporation */
 
 #include "igc.h"
+#include "igc_hw.h"
 #include "igc_tsn.h"
 
 static bool is_any_launchtime(struct igc_adapter *adapter)
@@ -92,7 +93,8 @@ static int igc_tsn_disable_offload(struct igc_adapter *adapter)
 
 	tqavctrl = rd32(IGC_TQAVCTRL);
 	tqavctrl &= ~(IGC_TQAVCTRL_TRANSMIT_MODE_TSN |
-		      IGC_TQAVCTRL_ENHANCED_QAV);
+		      IGC_TQAVCTRL_ENHANCED_QAV | IGC_TQAVCTRL_FUTSCDDIS);
+
 	wr32(IGC_TQAVCTRL, tqavctrl);
 
 	for (i = 0; i < adapter->num_tx_queues; i++) {
@@ -117,20 +119,10 @@ static int igc_tsn_enable_offload(struct igc_adapter *adapter)
 	ktime_t base_time, systim;
 	int i;
 
-	cycle = adapter->cycle_time;
-	base_time = adapter->base_time;
-
 	wr32(IGC_TSAUXC, 0);
 	wr32(IGC_DTXMXPKTSZ, IGC_DTXMXPKTSZ_TSN);
 	wr32(IGC_TXPBS, IGC_TXPBSIZE_TSN);
 
-	tqavctrl = rd32(IGC_TQAVCTRL);
-	tqavctrl |= IGC_TQAVCTRL_TRANSMIT_MODE_TSN | IGC_TQAVCTRL_ENHANCED_QAV;
-	wr32(IGC_TQAVCTRL, tqavctrl);
-
-	wr32(IGC_QBVCYCLET_S, cycle);
-	wr32(IGC_QBVCYCLET, cycle);
-
 	for (i = 0; i < adapter->num_tx_queues; i++) {
 		struct igc_ring *ring = adapter->tx_ring[i];
 		u32 txqctl = 0;
@@ -233,21 +225,43 @@ skip_cbs:
 		wr32(IGC_TXQCTL(i), txqctl);
 	}
 
+	tqavctrl = rd32(IGC_TQAVCTRL);
+	tqavctrl |= IGC_TQAVCTRL_TRANSMIT_MODE_TSN | IGC_TQAVCTRL_ENHANCED_QAV;
+
+	cycle = adapter->cycle_time;
+	base_time = adapter->base_time;
+
 	nsec = rd32(IGC_SYSTIML);
 	sec = rd32(IGC_SYSTIMH);
 
 	systim = ktime_set(sec, nsec);
-
 	if (ktime_compare(systim, base_time) > 0) {
-		s64 n;
+		s64 n = div64_s64(ktime_sub_ns(systim, base_time), cycle);
 
-		n = div64_s64(ktime_sub_ns(systim, base_time), cycle);
 		base_time = ktime_add_ns(base_time, (n + 1) * cycle);
+	} else {
+		/* According to datasheet section 7.5.2.9.3.3, FutScdDis bit
+		 * has to be configured before the cycle time and base time.
+		 */
+		if (igc_is_device_id_i226(hw))
+			tqavctrl |= IGC_TQAVCTRL_FUTSCDDIS;
 	}
 
-	baset_h = div_s64_rem(base_time, NSEC_PER_SEC, &baset_l);
+	wr32(IGC_TQAVCTRL, tqavctrl);
+
+	wr32(IGC_QBVCYCLET_S, cycle);
+	wr32(IGC_QBVCYCLET, cycle);
 
+	baset_h = div_s64_rem(base_time, NSEC_PER_SEC, &baset_l);
 	wr32(IGC_BASET_H, baset_h);
+
+	/* In i226, Future base time is only supported when FutScdDis bit
+	 * is enabled and only active for re-configuration.
+	 * In this case, initialize the base time with zero to create
+	 * "re-configuration" scenario then only set the desired base time.
+	 */
+	if (tqavctrl & IGC_TQAVCTRL_FUTSCDDIS)
+		wr32(IGC_BASET_L, 0);
 	wr32(IGC_BASET_L, baset_l);
 
 	return 0;