Re: [PATCH net-next v6 2/2] net: ti: icssg-prueth: Add ethtool ops for Frame Preemption MAC Merge

[Maxime Chevallier <maxime.chevallier@bootlin.com>]

Hi,

On 5/25/26 20:27, Meghana Malladi wrote:
> From: MD Danish Anwar <danishanwar@ti.com>
> 
> Add driver support for viewing and changing the MAC Merge sublayer
> parameters via ethtool ops: .set_mm(), .get_mm() and .get_mm_stats().
> 
> The minimum size of non-final mPacket fragments supported by the firmware
> without leading errors is 64 Bytes (including FCS). Verify time bounded to
> 1-128 ms per 802.3-2018 clause 30.14.1.6. Add a check to ensure
> user passed tx_min_frag_size argument via ethtool, honors this.
> Add pa stats registers to check statistics for preemption, which can be
> dumped using ethtool ops.
> 
> Fix emac_get_stat_by_name() to return u64 instead of int and return 0 on
> error instead of -EINVAL. This prevents invalid stat lookups from corrupting
> output stats with signed error codes cast to u64. Error conditions are still
> logged via netdev_err().
> 
> Signed-off-by: MD Danish Anwar <danishanwar@ti.com>
> Signed-off-by: Meghana Malladi <m-malladi@ti.com>
> ---
> 
> v6-v5:
> - Initialize tx_min_frag_size and verify_time with valid values
>    to avoid returning corrupted values during get_mm()
> - Fix rx_min_frag_size to ETH_ZLEN excluding ETH_FCS_LEN
> - Fix return codes for emac_set_mm()
> All the above changes address the comments raised by sashiko
> 
>   drivers/net/ethernet/ti/icssg/icssg_ethtool.c | 106 ++++++++++++++++++
>   drivers/net/ethernet/ti/icssg/icssg_prueth.h  |   7 +-
>   drivers/net/ethernet/ti/icssg/icssg_qos.h     |  46 ++++++++
>   drivers/net/ethernet/ti/icssg/icssg_stats.c   |   4 +-
>   drivers/net/ethernet/ti/icssg/icssg_stats.h   |   7 +-
>   .../net/ethernet/ti/icssg/icssg_switch_map.h  |   5 +
>   6 files changed, 168 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/net/ethernet/ti/icssg/icssg_ethtool.c b/drivers/net/ethernet/ti/icssg/icssg_ethtool.c
> index b715af21d23ac..ee940051644d6 100644
> --- a/drivers/net/ethernet/ti/icssg/icssg_ethtool.c
> +++ b/drivers/net/ethernet/ti/icssg/icssg_ethtool.c
> @@ -294,6 +294,109 @@ static int emac_set_per_queue_coalesce(struct net_device *ndev, u32 queue,
>   	return 0;
>   }
>   
> +static int emac_get_mm(struct net_device *ndev, struct ethtool_mm_state *state)
> +{
> +	struct prueth_emac *emac = netdev_priv(ndev);
> +	struct prueth_qos_iet *iet = &emac->qos.iet;
> +	enum icssg_ietfpe_verify_states verify_status;
> +
> +	if (emac->is_sr1)
> +		return -EOPNOTSUPP;
> +
> +	mutex_lock(&iet->fpe_lock);
> +	state->tx_enabled = iet->fpe_enabled;
> +	state->tx_min_frag_size = iet->tx_min_frag_size;
> +	state->tx_active = iet->fpe_active;
> +	state->verify_enabled = iet->mac_verify_configure;
> +	state->verify_time = iet->verify_time_ms;
> +	verify_status = iet->verify_status;
> +	mutex_unlock(&iet->fpe_lock);
> +
> +	state->rx_min_frag_size = ETH_ZLEN;
> +	state->pmac_enabled = true;
> +
> +	switch (verify_status) {
> +	case ICSSG_IETFPE_STATE_DISABLED:
> +		state->verify_status = ETHTOOL_MM_VERIFY_STATUS_DISABLED;
> +		break;
> +	case ICSSG_IETFPE_STATE_INITIAL:
> +		state->verify_status = ETHTOOL_MM_VERIFY_STATUS_INITIAL;
> +		break;
> +	case ICSSG_IETFPE_STATE_VERIFYING:
> +		state->verify_status = ETHTOOL_MM_VERIFY_STATUS_VERIFYING;
> +		break;
> +	case ICSSG_IETFPE_STATE_SUCCEEDED:
> +		state->verify_status = ETHTOOL_MM_VERIFY_STATUS_SUCCEEDED;
> +		break;
> +	case ICSSG_IETFPE_STATE_FAILED:
> +		state->verify_status = ETHTOOL_MM_VERIFY_STATUS_FAILED;
> +		break;
> +	default:
> +		state->verify_status = ETHTOOL_MM_VERIFY_STATUS_UNKNOWN;
> +		break;
> +	}
> +
> +	/* 802.3-2018 clause 30.14.1.6, says that the aMACMergeVerifyTime
> +	 * variable has a range between 1 and 128 ms inclusive. Limit to that.
> +	 */
> +	state->max_verify_time = ETHTOOL_MM_MAX_VERIFY_TIME_MS;
> +
> +	return 0;
> +}
> +
> +static int emac_set_mm(struct net_device *ndev, struct ethtool_mm_cfg *cfg,
> +		       struct netlink_ext_ack *extack)
> +{
> +	struct prueth_emac *emac = netdev_priv(ndev);
> +	struct prueth_qos_iet *iet = &emac->qos.iet;
> +	int err;
> +
> +	if (emac->is_sr1)
> +		return -EOPNOTSUPP;
> +
> +	if (!cfg->pmac_enabled) {
> +		NL_SET_ERR_MSG_MOD(extack, "preemptible MAC is always enabled");
> +		return -EOPNOTSUPP;
> +	}
> +
> +	err = icssg_qos_validate_tx_min_frag_size(cfg->tx_min_frag_size, extack);
> +	if (err)
> +		return err;
> +
> +	err = icssg_qos_validate_verify_time(cfg->verify_time, extack);
> +	if (err)
> +		return err;

The ethnl code already validates the verify_time :

https://elixir.bootlin.com/linux/v7.0.9/source/net/ethtool/mm.c#L153

> +
> +	mutex_lock(&iet->fpe_lock);
> +	iet->verify_time_ms = cfg->verify_time;
> +	iet->tx_min_frag_size = cfg->tx_min_frag_size;
> +	iet->fpe_enabled = cfg->tx_enabled;
> +	iet->mac_verify_configure = cfg->verify_enabled;
> +	err = icssg_config_ietfpe(ndev, cfg->tx_enabled);
> +	mutex_unlock(&iet->fpe_lock);
> +
> +	return err;
> +}
> +
> +static void emac_get_mm_stats(struct net_device *ndev,
> +			      struct ethtool_mm_stats *s)
> +{
> +	struct prueth_emac *emac = netdev_priv(ndev);
> +
> +	if (emac->is_sr1)
> +		return;
> +
> +	if (!emac->prueth->pa_stats)
> +		return;
> +
> +	/* MACMergeHoldCount stats is not tracked by the firmware */
> +	s->MACMergeFrameAssOkCount = emac_get_stat_by_name(emac, "FW_PREEMPT_ASSEMBLY_OK");
> +	s->MACMergeFrameAssErrorCount = emac_get_stat_by_name(emac, "FW_PREEMPT_ASSEMBLY_ERR");
> +	s->MACMergeFragCountRx = emac_get_stat_by_name(emac, "FW_PREEMPT_FRAG_CNT_RX");
> +	s->MACMergeFragCountTx = emac_get_stat_by_name(emac, "FW_PREEMPT_FRAG_CNT_TX");
> +	s->MACMergeFrameSmdErrorCount = emac_get_stat_by_name(emac, "FW_PREEMPT_BAD_FRAG");
> +}
> +
>   const struct ethtool_ops icssg_ethtool_ops = {
>   	.get_drvinfo = emac_get_drvinfo,
>   	.get_msglevel = emac_get_msglevel,
> @@ -317,5 +420,8 @@ const struct ethtool_ops icssg_ethtool_ops = {
>   	.set_eee = emac_set_eee,
>   	.nway_reset = emac_nway_reset,
>   	.get_rmon_stats = emac_get_rmon_stats,
> +	.get_mm = emac_get_mm,
> +	.set_mm = emac_set_mm,
> +	.get_mm_stats = emac_get_mm_stats,
>   };
>   EXPORT_SYMBOL_GPL(icssg_ethtool_ops);
> diff --git a/drivers/net/ethernet/ti/icssg/icssg_prueth.h b/drivers/net/ethernet/ti/icssg/icssg_prueth.h
> index 85f7017d2c8e7..61320c252bec2 100644
> --- a/drivers/net/ethernet/ti/icssg/icssg_prueth.h
> +++ b/drivers/net/ethernet/ti/icssg/icssg_prueth.h
> @@ -45,6 +45,7 @@
>   #include "icss_iep.h"
>   #include "icssg_switch_map.h"
>   #include "icssg_qos.h"
> +#include "icssg_stats.h"
>   
>   #define PRUETH_MAX_MTU          (2000 - ETH_HLEN - ETH_FCS_LEN)
>   #define PRUETH_MIN_PKT_SIZE     (VLAN_ETH_ZLEN)
> @@ -58,8 +59,8 @@
>   
>   #define ICSSG_MAX_RFLOWS	8	/* per slice */
>   
> -#define ICSSG_NUM_PA_STATS	32
> -#define ICSSG_NUM_MIIG_STATS	60
> +#define ICSSG_NUM_PA_STATS	ARRAY_SIZE(icssg_all_pa_stats)
> +#define ICSSG_NUM_MIIG_STATS	ARRAY_SIZE(icssg_all_miig_stats)
>   /* Number of ICSSG related stats */
>   #define ICSSG_NUM_STATS (ICSSG_NUM_MIIG_STATS + ICSSG_NUM_PA_STATS)
>   #define ICSSG_NUM_STANDARD_STATS 31
> @@ -460,7 +461,7 @@ int emac_fdb_flow_id_updated(struct prueth_emac *emac);
>   
>   void icssg_stats_work_handler(struct work_struct *work);
>   void emac_update_hardware_stats(struct prueth_emac *emac);
> -int emac_get_stat_by_name(struct prueth_emac *emac, char *stat_name);
> +u64 emac_get_stat_by_name(struct prueth_emac *emac, char *stat_name);
>   
>   /* Common functions */
>   void prueth_cleanup_rx_chns(struct prueth_emac *emac,
> diff --git a/drivers/net/ethernet/ti/icssg/icssg_qos.h b/drivers/net/ethernet/ti/icssg/icssg_qos.h
> index 9355e96bbcda8..87ca031afcaa4 100644
> --- a/drivers/net/ethernet/ti/icssg/icssg_qos.h
> +++ b/drivers/net/ethernet/ti/icssg/icssg_qos.h
> @@ -13,6 +13,7 @@
>   #define ICSSG_EXPRESS_Q_MASK_ALL		0xFF
>   #define ICSSG_IET_MAX_VERIFY_TIME		128
>   #define ICSSG_IET_MIN_VERIFY_TIME		1
> +#define ICSSG_IET_MAX_TX_MIN_FRAG_SIZE		252
>   
>   /**
>    * enum icssg_ietfpe_verify_states - status of MAC Merge Verify returned by firmware
> @@ -63,4 +64,49 @@ void icssg_qos_link_state_update(struct net_device *ndev);
>   int icssg_qos_ndo_setup_tc(struct net_device *ndev, enum tc_setup_type type,
>   			   void *type_data);
>   int icssg_config_ietfpe(struct net_device *ndev, bool enable);
> +static inline int icssg_qos_validate_tx_min_frag_size(u32 min_frag_size,
> +						      struct netlink_ext_ack *extack)
> +{
> +	/* Firmware takes min_frag_size including FCS length.
> +	 * The firmware requires the fragment size (including FCS) to be
> +	 * a multiple of 64 bytes. Since 64 bytes = ETH_ZLEN + ETH_FCS_LEN,
> +	 * valid user-facing values are: 60, 124, 188, 252.
> +	 */
> +
> +	if (min_frag_size < ETH_ZLEN) {
> +		NL_SET_ERR_MSG_MOD(extack,
> +				   "tx_min_frag_size must be at least 60 bytes");
> +		return -EINVAL;
> +	}
> +
> +	if (min_frag_size > ICSSG_IET_MAX_TX_MIN_FRAG_SIZE) {
> +		NL_SET_ERR_MSG_MOD(extack,
> +				   "tx_min_frag_size must not exceed 252 bytes");
> +		return -EINVAL;
> +	}
> +
> +	if ((min_frag_size + ETH_FCS_LEN) % (ETH_ZLEN + ETH_FCS_LEN)) {
> +		NL_SET_ERR_MSG_MOD(extack,
> +				   "tx_min_frag_size must be a multiple of 64 bytes minus 4");
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}

Is there any reason this helper is in a header file instead
of being directly in icssg_ethtool.c ?

> +
> +static inline int icssg_qos_validate_verify_time(u32 verify_time_ms,
> +						 struct netlink_ext_ack *extack)
> +{
> +	/* 802.3-2018 clause 30.14.1.6: aMACMergeVerifyTime must be
> +	 * between 1 and 128 ms inclusive
> +	 */
> +	if (verify_time_ms < ICSSG_IET_MIN_VERIFY_TIME ||
> +	    verify_time_ms > ICSSG_IET_MAX_VERIFY_TIME) {
> +		NL_SET_ERR_MSG_MOD(extack,
> +				   "verify_time must be between 1 and 128 ms");
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}

And this shouldn't be needed as the ethnl mm code already validates
these boundaries, as they are straight from the standard.

>   #endif /* __NET_TI_ICSSG_QOS_H */
> diff --git a/drivers/net/ethernet/ti/icssg/icssg_stats.c b/drivers/net/ethernet/ti/icssg/icssg_stats.c
> index 7159baa0155cf..cfdb6f5dc5da1 100644
> --- a/drivers/net/ethernet/ti/icssg/icssg_stats.c
> +++ b/drivers/net/ethernet/ti/icssg/icssg_stats.c
> @@ -74,7 +74,7 @@ void icssg_stats_work_handler(struct work_struct *work)
>   }
>   EXPORT_SYMBOL_GPL(icssg_stats_work_handler);
>   
> -int emac_get_stat_by_name(struct prueth_emac *emac, char *stat_name)
> +u64 emac_get_stat_by_name(struct prueth_emac *emac, char *stat_name)
>   {
>   	int i;
>   
> @@ -91,5 +91,5 @@ int emac_get_stat_by_name(struct prueth_emac *emac, char *stat_name)
>   	}
>   
>   	netdev_err(emac->ndev, "Invalid stats %s\n", stat_name);
> -	return -EINVAL;
> +	return 0;
>   }
> diff --git a/drivers/net/ethernet/ti/icssg/icssg_stats.h b/drivers/net/ethernet/ti/icssg/icssg_stats.h
> index 5ec0b38e0c67d..8073deac35c3e 100644
> --- a/drivers/net/ethernet/ti/icssg/icssg_stats.h
> +++ b/drivers/net/ethernet/ti/icssg/icssg_stats.h
> @@ -8,8 +8,6 @@
>   #ifndef __NET_TI_ICSSG_STATS_H
>   #define __NET_TI_ICSSG_STATS_H
>   
> -#include "icssg_prueth.h"
> -
>   #define STATS_TIME_LIMIT_1G_MS    25000    /* 25 seconds @ 1G */
>   
>   struct miig_stats_regs {
> @@ -189,6 +187,11 @@ static const struct icssg_pa_stats icssg_all_pa_stats[] = {
>   	ICSSG_PA_STATS(FW_INF_DROP_PRIOTAGGED),
>   	ICSSG_PA_STATS(FW_INF_DROP_NOTAG),
>   	ICSSG_PA_STATS(FW_INF_DROP_NOTMEMBER),
> +	ICSSG_PA_STATS(FW_PREEMPT_BAD_FRAG),
> +	ICSSG_PA_STATS(FW_PREEMPT_ASSEMBLY_ERR),
> +	ICSSG_PA_STATS(FW_PREEMPT_FRAG_CNT_TX),
> +	ICSSG_PA_STATS(FW_PREEMPT_ASSEMBLY_OK),
> +	ICSSG_PA_STATS(FW_PREEMPT_FRAG_CNT_RX),
>   	ICSSG_PA_STATS(FW_RX_EOF_SHORT_FRMERR),
>   	ICSSG_PA_STATS(FW_RX_B0_DROP_EARLY_EOF),
>   	ICSSG_PA_STATS(FW_TX_JUMBO_FRM_CUTOFF),
> diff --git a/drivers/net/ethernet/ti/icssg/icssg_switch_map.h b/drivers/net/ethernet/ti/icssg/icssg_switch_map.h
> index 7e053b8af3ece..855fd4ed0b3f6 100644
> --- a/drivers/net/ethernet/ti/icssg/icssg_switch_map.h
> +++ b/drivers/net/ethernet/ti/icssg/icssg_switch_map.h
> @@ -256,6 +256,11 @@
>   #define FW_INF_DROP_PRIOTAGGED		0x0148
>   #define FW_INF_DROP_NOTAG		0x0150
>   #define FW_INF_DROP_NOTMEMBER		0x0158
> +#define FW_PREEMPT_BAD_FRAG		0x0160
> +#define FW_PREEMPT_ASSEMBLY_ERR		0x0168
> +#define FW_PREEMPT_FRAG_CNT_TX		0x0170
> +#define FW_PREEMPT_ASSEMBLY_OK		0x0178
> +#define FW_PREEMPT_FRAG_CNT_RX		0x0180
>   #define FW_RX_EOF_SHORT_FRMERR		0x0188
>   #define FW_RX_B0_DROP_EARLY_EOF		0x0190
>   #define FW_TX_JUMBO_FRM_CUTOFF		0x0198

Maxime