[Intel-wired-lan] [next-queue PATCH v3 2/2] igc: Add support for ETF offloading

[Brown, Aaron F <aaron.f.brown@intel.com>]

> From: Intel-wired-lan <intel-wired-lan-bounces@osuosl.org> On Behalf Of
> Vinicius Costa Gomes
> Sent: Friday, February 14, 2020 3:52 PM
> To: intel-wired-lan at lists.osuosl.org
> Subject: [Intel-wired-lan] [next-queue PATCH v3 2/2] igc: Add support for
> ETF offloading
> 
> This adds support for ETF offloading for the i225 controller.
> 
> For i225, the LaunchTime feature is almost a subset of the Qbv
> feature. The main change from the i210 is that the launchtime of each
> packet is specified as an offset applied to the BASET register. BASET
> is automatically incremented each cycle.
> 
> For i225, the approach chosen is to re-use most of the setup used for
> taprio offloading. With a few changes:
> 
>  - The more or less obvious one is that when ETF is enabled, we should
>  set add the expected launchtime to the (advanced) transmit
>  descriptor;
> 
>  - The less obvious, is that when taprio offloading is not enabled, we
>  add a dummy schedule (all queues are open all the time, with a cycle
>  time of 1 second).
> 
> Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
> ---
>  drivers/net/ethernet/intel/igc/igc_defines.h |  1 +
>  drivers/net/ethernet/intel/igc/igc_main.c    | 70 +++++++++++++++++++-
>  drivers/net/ethernet/intel/igc/igc_tsn.c     | 19 +++++-
>  3 files changed, 86 insertions(+), 4 deletions(-)
> 
I'm using the TSN Scheduled TX Tools from https://gist.github.com/jeez/bd3afeff081ba64a695008dd8215866f, and the process (from both the README.etf and README.taprio) seems to work fine with an i210 (igb adapter) but when I try to use the same process with an i225 (igc based adapter) I get a series of Tx Unit Hangs when I start sending traffic.  Packets are still getting sent, but lot of ones just hang.
------------------------------------------------------------
[  936.406229] igc 0000:01:00.0: Detected Tx Unit Hang
                 Tx Queue             <0>
                 TDH                  <de>
                 TDT                  <e4>
                 next_to_use          <e4>
                 next_to_clean        <de>
               buffer_info[next_to_clean]
                 time_stamp           <100099d84>
                 next_to_watch        <0000000052519a89>
                 jiffies              <10009a393>
                 desc.status          <4a8200>
[  941.932530] igc 0000:01:00.0: Detected Tx Unit Hang
                 Tx Queue             <0>
                 TDH                  <1e>
                 TDT                  <22>
                 next_to_use          <22>
                 next_to_clean        <1e>
               buffer_info[next_to_clean]
                 time_stamp           <10009b0e0>
                 next_to_watch        <00000000ff485dca>
                 jiffies              <10009bb52>
                 desc.status          <4a8200>
[  945.581031] igc 0000:01:00.0: Detected Tx Unit Hang
                 Tx Queue             <0>
                 TDH                  <4a>
                 TDT                  <52>
                 next_to_use          <52>
                 next_to_clean        <4a>
               buffer_info[next_to_clean]
                 time_stamp           <10009c388>
                 next_to_watch        <00000000073a6ad3>
                 jiffies              <10009caff>
                 desc.status          <4a8200>

...
And so on until I stop the talker.  Other (regular) traffic still gets through without any apparent problem.  But only a portion of the etf scheduled ones, the rest left TX Hanging.

> diff --git a/drivers/net/ethernet/intel/igc/igc_defines.h
> b/drivers/net/ethernet/intel/igc/igc_defines.h
> index 3077d0a69b04..0746fa42ff3f 100644
> --- a/drivers/net/ethernet/intel/igc/igc_defines.h
> +++ b/drivers/net/ethernet/intel/igc/igc_defines.h
> @@ -440,6 +440,7 @@
>  #define IGC_TQAVCTRL_TRANSMIT_MODE_TSN	0x00000001
>  #define IGC_TQAVCTRL_ENHANCED_QAV	0x00000008
> 
> +#define IGC_TXQCTL_QUEUE_MODE_LAUNCHT	0x00000001
>  #define IGC_TXQCTL_STRICT_CYCLE		0x00000002
>  #define IGC_TXQCTL_STRICT_END		0x00000004
> 
> diff --git a/drivers/net/ethernet/intel/igc/igc_main.c
> b/drivers/net/ethernet/intel/igc/igc_main.c
> index 5fb52768de18..55ab6077455d 100644
> --- a/drivers/net/ethernet/intel/igc/igc_main.c
> +++ b/drivers/net/ethernet/intel/igc/igc_main.c
> @@ -869,6 +869,23 @@ static int igc_write_mc_addr_list(struct net_device
> *netdev)
>  	return netdev_mc_count(netdev);
>  }
> 
> +static __le32 igc_tx_launchtime(struct igc_adapter *adapter, ktime_t
> txtime)
> +{
> +	ktime_t cycle_time = adapter->cycle_time;
> +	ktime_t base_time = adapter->base_time;
> +	u32 launchtime;
> +
> +	/* FIXME: when using ETF together with taprio, we may have a
> +	 * case where 'delta' is larger than the cycle_time, this may
> +	 * cause problems if we don't read the current value of
> +	 * IGC_BASET, as the value writen into the launchtime
> +	 * descriptor field may be misinterpreted.
> +	 */
> +	div_s64_rem(ktime_sub_ns(txtime, base_time), cycle_time,
> &launchtime);
> +
> +	return cpu_to_le32(launchtime);
> +}
> +
>  static void igc_tx_ctxtdesc(struct igc_ring *tx_ring,
>  			    struct igc_tx_buffer *first,
>  			    u32 vlan_macip_lens, u32 type_tucmd,
> @@ -876,7 +893,6 @@ static void igc_tx_ctxtdesc(struct igc_ring *tx_ring,
>  {
>  	struct igc_adv_tx_context_desc *context_desc;
>  	u16 i = tx_ring->next_to_use;
> -	struct timespec64 ts;
> 
>  	context_desc = IGC_TX_CTXTDESC(tx_ring, i);
> 
> @@ -898,9 +914,12 @@ static void igc_tx_ctxtdesc(struct igc_ring *tx_ring,
>  	 * should have been handled by the upper layers.
>  	 */
>  	if (tx_ring->launchtime_enable) {
> -		ts = ktime_to_timespec64(first->skb->tstamp);
> +		struct igc_adapter *adapter = netdev_priv(tx_ring->netdev);
> +		ktime_t txtime = first->skb->tstamp;
> +
>  		first->skb->tstamp = ktime_set(0, 0);
> -		context_desc->launch_time = cpu_to_le32(ts.tv_nsec / 32);
> +		context_desc->launch_time = igc_tx_launchtime(adapter,
> +							      txtime);
>  	} else {
>  		context_desc->launch_time = 0;
>  	}
> @@ -4497,6 +4516,32 @@ static int igc_ioctl(struct net_device *netdev,
> struct ifreq *ifr, int cmd)
>  	}
>  }
> 
> +static int igc_save_launchtime_params(struct igc_adapter *adapter, int
> queue,
> +				      bool enable)
> +{
> +	struct igc_ring *ring;
> +	int i;
> +
> +	if (queue < 0 || queue >= adapter->num_tx_queues)
> +		return -EINVAL;
> +
> +	ring = adapter->tx_ring[queue];
> +	ring->launchtime_enable = enable;
> +
> +	if (adapter->base_time)
> +		return 0;
> +
> +	adapter->cycle_time = NSEC_PER_SEC;
> +
> +	for (i = 0; i < adapter->num_tx_queues; i++) {
> +		ring = adapter->tx_ring[i];
> +		ring->start_time = 0;
> +		ring->end_time = NSEC_PER_SEC;
> +	}
> +
> +	return 0;
> +}
> +
>  static bool validate_schedule(const struct tc_taprio_qopt_offload *qopt)
>  {
>  	int queue_uses[IGC_MAX_TX_QUEUES] = { };
> @@ -4529,6 +4574,22 @@ static bool validate_schedule(const struct
> tc_taprio_qopt_offload *qopt)
>  	return true;
>  }
> 
> +static int igc_tsn_enable_launchtime(struct igc_adapter *adapter,
> +				     struct tc_etf_qopt_offload *qopt)
> +{
> +	struct igc_hw *hw = &adapter->hw;
> +	int err;
> +
> +	if (hw->mac.type != igc_i225)
> +		return -EOPNOTSUPP;
> +
> +	err = igc_save_launchtime_params(adapter, qopt->queue, qopt-
> >enable);
> +	if (err)
> +		return err;
> +
> +	return igc_tsn_offload_apply(adapter);
> +}
> +
>  static int igc_save_qbv_schedule(struct igc_adapter *adapter,
>  				 struct tc_taprio_qopt_offload *qopt)
>  {
> @@ -4599,6 +4660,9 @@ static int igc_setup_tc(struct net_device *dev,
> enum tc_setup_type type,
>  	case TC_SETUP_QDISC_TAPRIO:
>  		return igc_tsn_enable_qbv_scheduling(adapter, type_data);
> 
> +	case TC_SETUP_QDISC_ETF:
> +		return igc_tsn_enable_launchtime(adapter, type_data);
> +
>  	default:
>  		return -EOPNOTSUPP;
>  	}
> diff --git a/drivers/net/ethernet/intel/igc/igc_tsn.c
> b/drivers/net/ethernet/intel/igc/igc_tsn.c
> index 257fe970afe8..174103c4bea6 100644
> --- a/drivers/net/ethernet/intel/igc/igc_tsn.c
> +++ b/drivers/net/ethernet/intel/igc/igc_tsn.c
> @@ -4,6 +4,20 @@
>  #include "igc.h"
>  #include "igc_tsn.h"
> 
> +static bool is_any_launchtime(struct igc_adapter *adapter)
> +{
> +	int i;
> +
> +	for (i = 0; i < adapter->num_tx_queues; i++) {
> +		struct igc_ring *ring = adapter->tx_ring[i];
> +
> +		if (ring->launchtime_enable)
> +			return true;
> +	}
> +
> +	return false;
> +}
> +
>  /* Returns the TSN specific registers to their default values after
>   * TSN offloading is disabled.
>   */
> @@ -88,6 +102,9 @@ static int igc_tsn_enable_offload(struct igc_adapter
> *adapter)
>  				IGC_TXQCTL_STRICT_END;
>  		}
> 
> +		if (ring->launchtime_enable)
> +			txqctl |= IGC_TXQCTL_QUEUE_MODE_LAUNCHT;
> +
>  		wr32(IGC_TXQCTL(i), txqctl);
>  	}
> 
> @@ -115,7 +132,7 @@ static int igc_tsn_enable_offload(struct igc_adapter
> *adapter)
> 
>  int igc_tsn_offload_apply(struct igc_adapter *adapter)
>  {
> -	bool is_any_enabled = adapter->base_time;
> +	bool is_any_enabled = adapter->base_time ||
> is_any_launchtime(adapter);
> 
>  	if (!(adapter->flags & IGC_FLAG_TSN_QBV_ENABLED) &&
> !is_any_enabled)
>  		return 0;
> --
> 2.25.0
> 
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