[PATCH net 0/4][pull request] Intel Wired LAN Driver Updates 2024-08-07 (igc)

[PATCH net 0/4][pull request] Intel Wired LAN Driver Updates 2024-08-07 (igc)

[Tony Nguyen]

This series contains updates to igc driver only.

Faizal adjusts the size of the MAC internal buffer on i226 devices to
resolve an errata for leaking packet transmits. He also corrects a
condition in which qbv_config_change_errors are incorrectly counted.
Lastly, he adjusts the conditions for resetting the adapter when
changing TSN Tx mode and corrects the conditions in which gtxoffset
register is set.

The following are changes since commit 1ca645a2f74a4290527ae27130c8611391b07dbf:
  net: usb: qmi_wwan: add MeiG Smart SRM825L
and are available in the git repository at:
  git://git.kernel.org/pub/scm/linux/kernel/git/tnguy/net-queue 1GbE

Faizal Rahim (4):
  igc: Fix packet still tx after gate close by reducing i226 MAC retry
    buffer
  igc: Fix qbv_config_change_errors logics
  igc: Fix reset adapter logics when tx mode change
  igc: Fix qbv tx latency by setting gtxoffset

 drivers/net/ethernet/intel/igc/igc_defines.h |  6 ++
 drivers/net/ethernet/intel/igc/igc_main.c    |  8 ++-
 drivers/net/ethernet/intel/igc/igc_tsn.c     | 76 ++++++++++++++++----
 drivers/net/ethernet/intel/igc/igc_tsn.h     |  1 +
 4 files changed, 75 insertions(+), 16 deletions(-)

-- 
2.42.0

[PATCH net 1/4] igc: Fix packet still tx after gate close by reducing i226 MAC retry buffer

[Tony Nguyen]

From: Faizal Rahim <faizal.abdul.rahim@linux.intel.com>

Testing uncovered that even when the taprio gate is closed, some packets
still transmit.

According to i225/6 hardware errata [1], traffic might overflow the
planned QBV window. This happens because MAC maintains an internal buffer,
primarily for supporting half duplex retries. Therefore, even when the
gate closes, residual MAC data in the buffer may still transmit.

To mitigate this for i226, reduce the MAC's internal buffer from 192 bytes
to the recommended 88 bytes by modifying the RETX_CTL register value.

This follows guidelines from:
[1] Ethernet Controller I225/I22 Spec Update Rev 2.1 Errata Item 9:
    TSN: Packet Transmission Might Cross Qbv Window
[2] I225/6 SW User Manual Rev 1.2.4: Section 8.11.5 Retry Buffer Control

Note that the RETX_CTL register can't be used in TSN mode because half
duplex feature cannot coexist with TSN.

Test Steps:
1.  Send taprio cmd to board A:
    tc qdisc replace dev enp1s0 parent root handle 100 taprio \
    num_tc 4 \
    map 3 2 1 0 3 3 3 3 3 3 3 3 3 3 3 3 \
    queues 1@0 1@1 1@2 1@3 \
    base-time 0 \
    sched-entry S 0x07 500000 \
    sched-entry S 0x0f 500000 \
    flags 0x2 \
    txtime-delay 0

    Note that for TC3, gate should open for 500us and close for another
    500us.

3.  Take tcpdump log on Board B.

4.  Send udp packets via UDP tai app from Board A to Board B.

5.  Analyze tcpdump log via wireshark log on Board B. Ensure that the
    total time from the first to the last packet received during one cycle
    for TC3 does not exceed 500us.

Fixes: 43546211738e ("igc: Add new device ID's")
Signed-off-by: Faizal Rahim <faizal.abdul.rahim@linux.intel.com>
Acked-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Tested-by: Mor Bar-Gabay <morx.bar.gabay@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
---
 drivers/net/ethernet/intel/igc/igc_defines.h |  6 ++++
 drivers/net/ethernet/intel/igc/igc_tsn.c     | 34 ++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/drivers/net/ethernet/intel/igc/igc_defines.h b/drivers/net/ethernet/intel/igc/igc_defines.h
index 5f92b3c7c3d4..511384f3ec5c 100644
--- a/drivers/net/ethernet/intel/igc/igc_defines.h
+++ b/drivers/net/ethernet/intel/igc/igc_defines.h
@@ -404,6 +404,12 @@
 #define IGC_DTXMXPKTSZ_TSN	0x19 /* 1600 bytes of max TX DMA packet size */
 #define IGC_DTXMXPKTSZ_DEFAULT	0x98 /* 9728-byte Jumbo frames */
 
+/* Retry Buffer Control */
+#define IGC_RETX_CTL			0x041C
+#define IGC_RETX_CTL_WATERMARK_MASK	0xF
+#define IGC_RETX_CTL_QBVFULLTH_SHIFT	8 /* QBV Retry Buffer Full Threshold */
+#define IGC_RETX_CTL_QBVFULLEN	0x1000 /* Enable QBV Retry Buffer Full Threshold */
+
 /* Transmit Scheduling Latency */
 /* Latency between transmission scheduling (LaunchTime) and the time
  * the packet is transmitted to the network in nanosecond.
diff --git a/drivers/net/ethernet/intel/igc/igc_tsn.c b/drivers/net/ethernet/intel/igc/igc_tsn.c
index 22cefb1eeedf..46d4c3275bbb 100644
--- a/drivers/net/ethernet/intel/igc/igc_tsn.c
+++ b/drivers/net/ethernet/intel/igc/igc_tsn.c
@@ -78,6 +78,15 @@ void igc_tsn_adjust_txtime_offset(struct igc_adapter *adapter)
 	wr32(IGC_GTXOFFSET, txoffset);
 }
 
+static void igc_tsn_restore_retx_default(struct igc_adapter *adapter)
+{
+	struct igc_hw *hw = &adapter->hw;
+	u32 retxctl;
+
+	retxctl = rd32(IGC_RETX_CTL) & IGC_RETX_CTL_WATERMARK_MASK;
+	wr32(IGC_RETX_CTL, retxctl);
+}
+
 /* Returns the TSN specific registers to their default values after
  * the adapter is reset.
  */
@@ -91,6 +100,9 @@ static int igc_tsn_disable_offload(struct igc_adapter *adapter)
 	wr32(IGC_TXPBS, I225_TXPBSIZE_DEFAULT);
 	wr32(IGC_DTXMXPKTSZ, IGC_DTXMXPKTSZ_DEFAULT);
 
+	if (igc_is_device_id_i226(hw))
+		igc_tsn_restore_retx_default(adapter);
+
 	tqavctrl = rd32(IGC_TQAVCTRL);
 	tqavctrl &= ~(IGC_TQAVCTRL_TRANSMIT_MODE_TSN |
 		      IGC_TQAVCTRL_ENHANCED_QAV | IGC_TQAVCTRL_FUTSCDDIS);
@@ -111,6 +123,25 @@ static int igc_tsn_disable_offload(struct igc_adapter *adapter)
 	return 0;
 }
 
+/* To partially fix i226 HW errata, reduce MAC internal buffering from 192 Bytes
+ * to 88 Bytes by setting RETX_CTL register using the recommendation from:
+ * a) Ethernet Controller I225/I226 Specification Update Rev 2.1
+ *    Item 9: TSN: Packet Transmission Might Cross the Qbv Window
+ * b) I225/6 SW User Manual Rev 1.2.4: Section 8.11.5 Retry Buffer Control
+ */
+static void igc_tsn_set_retx_qbvfullthreshold(struct igc_adapter *adapter)
+{
+	struct igc_hw *hw = &adapter->hw;
+	u32 retxctl, watermark;
+
+	retxctl = rd32(IGC_RETX_CTL);
+	watermark = retxctl & IGC_RETX_CTL_WATERMARK_MASK;
+	/* Set QBVFULLTH value using watermark and set QBVFULLEN */
+	retxctl |= (watermark << IGC_RETX_CTL_QBVFULLTH_SHIFT) |
+		   IGC_RETX_CTL_QBVFULLEN;
+	wr32(IGC_RETX_CTL, retxctl);
+}
+
 static int igc_tsn_enable_offload(struct igc_adapter *adapter)
 {
 	struct igc_hw *hw = &adapter->hw;
@@ -123,6 +154,9 @@ static int igc_tsn_enable_offload(struct igc_adapter *adapter)
 	wr32(IGC_DTXMXPKTSZ, IGC_DTXMXPKTSZ_TSN);
 	wr32(IGC_TXPBS, IGC_TXPBSIZE_TSN);
 
+	if (igc_is_device_id_i226(hw))
+		igc_tsn_set_retx_qbvfullthreshold(adapter);
+
 	for (i = 0; i < adapter->num_tx_queues; i++) {
 		struct igc_ring *ring = adapter->tx_ring[i];
 		u32 txqctl = 0;
-- 
2.42.0

[PATCH net 2/4] igc: Fix qbv_config_change_errors logics

[Tony Nguyen]

From: Faizal Rahim <faizal.abdul.rahim@linux.intel.com>

When user issues these cmds:
1. Either a) or b)
   a) mqprio with hardware offload disabled
   b) taprio with txtime-assist feature enabled
2. etf
3. tc qdisc delete
4. taprio with base time in the past

At step 4, qbv_config_change_errors wrongly increased by 1.

Excerpt from IEEE 802.1Q-2018 8.6.9.3.1:
"If AdminBaseTime specifies a time in the past, and the current schedule
is running, then: Increment ConfigChangeError counter"

qbv_config_change_errors should only increase if base time is in the past
and no taprio is active. In user perspective, taprio was not active when
first triggered at step 4. However, i225/6 reuses qbv for etf, so qbv is
enabled with a dummy schedule at step 2 where it enters
igc_tsn_enable_offload() and qbv_count got incremented to 1. At step 4, it
enters igc_tsn_enable_offload() again, qbv_count is incremented to 2.
Because taprio is running, tc_setup_type is TC_SETUP_QDISC_ETF and
qbv_count > 1, qbv_config_change_errors value got incremented.

This issue happens due to reliance on qbv_count field where a non-zero
value indicates that taprio is running. But qbv_count increases
regardless if taprio is triggered by user or by other tsn feature. It does
not align with qbv_config_change_errors expectation where it is only
concerned with taprio triggered by user.

Fixing this by relocating the qbv_config_change_errors logic to
igc_save_qbv_schedule(), eliminating reliance on qbv_count and its
inaccuracies from i225/6's multiple uses of qbv feature for other TSN
features.

The new function created: igc_tsn_is_taprio_activated_by_user() uses
taprio_offload_enable field to indicate that the current running taprio
was triggered by user, instead of triggered by non-qbv feature like etf.

Fixes: ae4fe4698300 ("igc: Add qbv_config_change_errors counter")
Signed-off-by: Faizal Rahim <faizal.abdul.rahim@linux.intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Acked-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Tested-by: Mor Bar-Gabay <morx.bar.gabay@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
---
 drivers/net/ethernet/intel/igc/igc_main.c |  8 ++++++--
 drivers/net/ethernet/intel/igc/igc_tsn.c  | 16 ++++++++--------
 drivers/net/ethernet/intel/igc/igc_tsn.h  |  1 +
 3 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index 8daf938afc36..dfd6c00b4205 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -6315,12 +6315,16 @@ static int igc_save_qbv_schedule(struct igc_adapter *adapter,
 	if (!validate_schedule(adapter, qopt))
 		return -EINVAL;
 
+	igc_ptp_read(adapter, &now);
+
+	if (igc_tsn_is_taprio_activated_by_user(adapter) &&
+	    is_base_time_past(qopt->base_time, &now))
+		adapter->qbv_config_change_errors++;
+
 	adapter->cycle_time = qopt->cycle_time;
 	adapter->base_time = qopt->base_time;
 	adapter->taprio_offload_enable = true;
 
-	igc_ptp_read(adapter, &now);
-
 	for (n = 0; n < qopt->num_entries; n++) {
 		struct tc_taprio_sched_entry *e = &qopt->entries[n];
 
diff --git a/drivers/net/ethernet/intel/igc/igc_tsn.c b/drivers/net/ethernet/intel/igc/igc_tsn.c
index 46d4c3275bbb..8ed7b965484d 100644
--- a/drivers/net/ethernet/intel/igc/igc_tsn.c
+++ b/drivers/net/ethernet/intel/igc/igc_tsn.c
@@ -87,6 +87,14 @@ static void igc_tsn_restore_retx_default(struct igc_adapter *adapter)
 	wr32(IGC_RETX_CTL, retxctl);
 }
 
+bool igc_tsn_is_taprio_activated_by_user(struct igc_adapter *adapter)
+{
+	struct igc_hw *hw = &adapter->hw;
+
+	return (rd32(IGC_BASET_H) || rd32(IGC_BASET_L)) &&
+		adapter->taprio_offload_enable;
+}
+
 /* Returns the TSN specific registers to their default values after
  * the adapter is reset.
  */
@@ -296,14 +304,6 @@ static int igc_tsn_enable_offload(struct igc_adapter *adapter)
 		s64 n = div64_s64(ktime_sub_ns(systim, base_time), cycle);
 
 		base_time = ktime_add_ns(base_time, (n + 1) * cycle);
-
-		/* Increase the counter if scheduling into the past while
-		 * Gate Control List (GCL) is running.
-		 */
-		if ((rd32(IGC_BASET_H) || rd32(IGC_BASET_L)) &&
-		    (adapter->tc_setup_type == TC_SETUP_QDISC_TAPRIO) &&
-		    (adapter->qbv_count > 1))
-			adapter->qbv_config_change_errors++;
 	} else {
 		if (igc_is_device_id_i226(hw)) {
 			ktime_t adjust_time, expires_time;
diff --git a/drivers/net/ethernet/intel/igc/igc_tsn.h b/drivers/net/ethernet/intel/igc/igc_tsn.h
index b53e6af560b7..98ec845a86bf 100644
--- a/drivers/net/ethernet/intel/igc/igc_tsn.h
+++ b/drivers/net/ethernet/intel/igc/igc_tsn.h
@@ -7,5 +7,6 @@
 int igc_tsn_offload_apply(struct igc_adapter *adapter);
 int igc_tsn_reset(struct igc_adapter *adapter);
 void igc_tsn_adjust_txtime_offset(struct igc_adapter *adapter);
+bool igc_tsn_is_taprio_activated_by_user(struct igc_adapter *adapter);
 
 #endif /* _IGC_BASE_H */
-- 
2.42.0

[PATCH net 3/4] igc: Fix reset adapter logics when tx mode change

[Tony Nguyen]

From: Faizal Rahim <faizal.abdul.rahim@linux.intel.com>

Following the "igc: Fix TX Hang issue when QBV Gate is close" changes,
remaining issues with the reset adapter logic in igc_tsn_offload_apply()
have been observed:

1. The reset adapter logics for i225 and i226 differ, although they should
   be the same according to the guidelines in I225/6 HW Design Section
   7.5.2.1 on software initialization during tx mode changes.
2. The i225 resets adapter every time, even though tx mode doesn't change.
   This occurs solely based on the condition  igc_is_device_id_i225() when
   calling schedule_work().
3. i226 doesn't reset adapter for tsn->legacy tx mode changes. It only
   resets adapter for legacy->tsn tx mode transitions.
4. qbv_count introduced in the patch is actually not needed; in this
   context, a non-zero value of qbv_count is used to indicate if tx mode
   was unconditionally set to tsn in igc_tsn_enable_offload(). This could
   be replaced by checking the existing register
   IGC_TQAVCTRL_TRANSMIT_MODE_TSN bit.

This patch resolves all issues and enters schedule_work() to reset the
adapter only when changing tx mode. It also removes reliance on qbv_count.

qbv_count field will be removed in a future patch.

Test ran:

1. Verify reset adapter behaviour in i225/6:
   a) Enrol a new GCL
      Reset adapter observed (tx mode change legacy->tsn)
   b) Enrol a new GCL without deleting qdisc
      No reset adapter observed (tx mode remain tsn->tsn)
   c) Delete qdisc
      Reset adapter observed (tx mode change tsn->legacy)

2. Tested scenario from "igc: Fix TX Hang issue when QBV Gate is closed"
   to confirm it remains resolved.

Fixes: 175c241288c0 ("igc: Fix TX Hang issue when QBV Gate is closed")
Signed-off-by: Faizal Rahim <faizal.abdul.rahim@linux.intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Acked-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Tested-by: Mor Bar-Gabay <morx.bar.gabay@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
---
 drivers/net/ethernet/intel/igc/igc_tsn.c | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_tsn.c b/drivers/net/ethernet/intel/igc/igc_tsn.c
index 8ed7b965484d..ada751430517 100644
--- a/drivers/net/ethernet/intel/igc/igc_tsn.c
+++ b/drivers/net/ethernet/intel/igc/igc_tsn.c
@@ -49,6 +49,13 @@ static unsigned int igc_tsn_new_flags(struct igc_adapter *adapter)
 	return new_flags;
 }
 
+static bool igc_tsn_is_tx_mode_in_tsn(struct igc_adapter *adapter)
+{
+	struct igc_hw *hw = &adapter->hw;
+
+	return !!(rd32(IGC_TQAVCTRL) & IGC_TQAVCTRL_TRANSMIT_MODE_TSN);
+}
+
 void igc_tsn_adjust_txtime_offset(struct igc_adapter *adapter)
 {
 	struct igc_hw *hw = &adapter->hw;
@@ -365,15 +372,22 @@ int igc_tsn_reset(struct igc_adapter *adapter)
 	return err;
 }
 
-int igc_tsn_offload_apply(struct igc_adapter *adapter)
+static bool igc_tsn_will_tx_mode_change(struct igc_adapter *adapter)
 {
-	struct igc_hw *hw = &adapter->hw;
+	bool any_tsn_enabled = !!(igc_tsn_new_flags(adapter) &
+				  IGC_FLAG_TSN_ANY_ENABLED);
+
+	return (any_tsn_enabled && !igc_tsn_is_tx_mode_in_tsn(adapter)) ||
+	       (!any_tsn_enabled && igc_tsn_is_tx_mode_in_tsn(adapter));
+}
 
-	/* Per I225/6 HW Design Section 7.5.2.1, transmit mode
-	 * cannot be changed dynamically. Require reset the adapter.
+int igc_tsn_offload_apply(struct igc_adapter *adapter)
+{
+	/* Per I225/6 HW Design Section 7.5.2.1 guideline, if tx mode change
+	 * from legacy->tsn or tsn->legacy, then reset adapter is needed.
 	 */
 	if (netif_running(adapter->netdev) &&
-	    (igc_is_device_id_i225(hw) || !adapter->qbv_count)) {
+	    igc_tsn_will_tx_mode_change(adapter)) {
 		schedule_work(&adapter->reset_task);
 		return 0;
 	}
-- 
2.42.0

[PATCH net 4/4] igc: Fix qbv tx latency by setting gtxoffset

[Tony Nguyen]

From: Faizal Rahim <faizal.abdul.rahim@linux.intel.com>

A large tx latency issue was discovered during testing when only QBV was
enabled. The issue occurs because gtxoffset was not set when QBV is
active, it was only set when launch time is active.

The patch "igc: Correct the launchtime offset" only sets gtxoffset when
the launchtime_enable field is set by the user. Enabling launchtime_enable
ultimately sets the register IGC_TXQCTL_QUEUE_MODE_LAUNCHT (referred to as
LaunchT in the SW user manual).

Section 7.5.2.6 of the IGC i225/6 SW User Manual Rev 1.2.4 states:
"The latency between transmission scheduling (launch time) and the
time the packet is transmitted to the network is listed in Table 7-61."

However, the patch misinterprets the phrase "launch time" in that section
by assuming it specifically refers to the LaunchT register, whereas it
actually denotes the generic term for when a packet is released from the
internal buffer to the MAC transmit logic.

This launch time, as per that section, also implicitly refers to the QBV
gate open time, where a packet waits in the buffer for the QBV gate to
open. Therefore, latency applies whenever QBV is in use. TSN features such
as QBU and QAV reuse QBV, making the latency universal to TSN features.

Discussed with i226 HW owner (Shalev, Avi) and we were in agreement that
the term "launch time" used in Section 7.5.2.6 is not clear and can be
easily misinterpreted. Avi will update this section to:
"When TQAVCTRL.TRANSMIT_MODE = TSN, the latency between transmission
scheduling and the time the packet is transmitted to the network is listed
in Table 7-61."

Fix this issue by using igc_tsn_is_tx_mode_in_tsn() as a condition to
write to gtxoffset, aligning with the newly updated SW User Manual.

Tested:
1. Enrol taprio on talker board
   base-time 0
   cycle-time 1000000
   flags 0x2
   index 0 cmd S gatemask 0x1 interval1
   index 0 cmd S gatemask 0x1 interval2

   Note:
   interval1 = interval for a 64 bytes packet to go through
   interval2 = cycle-time - interval1

2. Take tcpdump on listener board

3. Use udp tai app on talker to send packets to listener

4. Check the timestamp on listener via wireshark

Test Result:
100 Mbps: 113 ~193 ns
1000 Mbps: 52 ~ 84 ns
2500 Mbps: 95 ~ 223 ns

Note that the test result is similar to the patch "igc: Correct the
launchtime offset".

Fixes: 790835fcc0cb ("igc: Correct the launchtime offset")
Signed-off-by: Faizal Rahim <faizal.abdul.rahim@linux.intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Acked-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Tested-by: Mor Bar-Gabay <morx.bar.gabay@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
---
 drivers/net/ethernet/intel/igc/igc_tsn.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_tsn.c b/drivers/net/ethernet/intel/igc/igc_tsn.c
index ada751430517..d68fa7f3d5f0 100644
--- a/drivers/net/ethernet/intel/igc/igc_tsn.c
+++ b/drivers/net/ethernet/intel/igc/igc_tsn.c
@@ -61,7 +61,7 @@ void igc_tsn_adjust_txtime_offset(struct igc_adapter *adapter)
 	struct igc_hw *hw = &adapter->hw;
 	u16 txoffset;
 
-	if (!is_any_launchtime(adapter))
+	if (!igc_tsn_is_tx_mode_in_tsn(adapter))
 		return;
 
 	switch (adapter->link_speed) {
-- 
2.42.0

Re: [PATCH net 0/4][pull request] Intel Wired LAN Driver Updates 2024-08-07 (igc)

[Jakub Kicinski]

On Wed,  7 Aug 2024 16:13:24 -0700 Tony Nguyen wrote:
> This series contains updates to igc driver only.
> 
> Faizal adjusts the size of the MAC internal buffer on i226 devices to
> resolve an errata for leaking packet transmits. He also corrects a
> condition in which qbv_config_change_errors are incorrectly counted.
> Lastly, he adjusts the conditions for resetting the adapter when
> changing TSN Tx mode and corrects the conditions in which gtxoffset
> register is set.

FTR appears to have been pulled, thanks!