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atlantic: add NET_DIM (Dynamic Interrupt Moderation) support #138

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atlantic: add NET_DIM (Dynamic Interrupt Moderation) support #138

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17a480c
atlantic: add NET_DIM (Dynamic Interrupt Moderation) support
8hodgsonkh Feb 24, 2026
9e1777d
atlantic: address review feedback on DIM patch
8hodgsonkh Feb 24, 2026
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225 changes: 225 additions & 0 deletions 6.19/0008-atlantic-dim.patch
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Original file line number Diff line number Diff line change
@@ -0,0 +1,225 @@
--- a/drivers/net/ethernet/aquantia/Kconfig 2026-02-16 16:11:45.000000000 +0000
+++ b/drivers/net/ethernet/aquantia/Kconfig 2026-02-23 01:33:03.716143177 +0000
@@ -20,6 +20,7 @@
tristate "aQuantia AQtion(tm) Support"
depends on PCI
depends on MACSEC || MACSEC=n
+ select NET_DIM
help
This enables the support for the aQuantia AQtion(tm) Ethernet card.

--- a/drivers/net/ethernet/aquantia/atlantic/aq_nic.h 2026-02-16 16:11:45.000000000 +0000
+++ b/drivers/net/ethernet/aquantia/atlantic/aq_nic.h 2026-02-23 01:33:13.450057021 +0000
@@ -12,6 +12,7 @@

#include <linux/ethtool.h>
#include <net/xdp.h>
+#include <linux/dim.h>
#include <linux/bpf.h>

#include "aq_common.h"
@@ -49,6 +50,8 @@
u32 itr;
u16 rx_itr;
u16 tx_itr;
+ bool is_rx_adaptive;
+ bool is_tx_adaptive;
u32 rxpageorder;
u32 num_rss_queues;
u32 mtu;
@@ -128,6 +131,10 @@
atomic_t flags;
u32 msg_enable;
struct aq_vec_s *aq_vec[AQ_CFG_VECS_MAX];
+ /* DIM (Dynamic Interrupt Moderation) state */
+ struct dim rx_dim;
+ struct dim tx_dim;
+ u16 dim_event_ctr;

Copilot AI Feb 24, 2026

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dim_event_ctr is declared as u16, but it is used as the monotonically increasing event_ctr input to dim_update_sample(). A 16-bit counter will wrap quickly and can confuse DIM’s rate calculations. Consider using a wider type (e.g., u32/u64) for the event counter (and keep it monotonically increasing for the lifetime of the DIM instance).

Suggested change
+ u16 dim_event_ctr;
+ u32 dim_event_ctr;

Copilot uses AI. Check for mistakes.
struct aq_ring_s *aq_ring_tx[AQ_HW_QUEUES_MAX];
struct aq_hw_s *aq_hw;
struct bpf_prog *xdp_prog;
@@ -218,4 +225,7 @@
const u32 max_rate);
int aq_nic_setup_tc_min_rate(struct aq_nic_s *self, const unsigned int tc,
const u32 min_rate);
+
+void aq_nic_dim_update(struct aq_nic_s *self);

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aq_nic_dim_update() is only referenced within aq_nic.c in this patch, but it’s declared in aq_nic.h and defined non-static. If no other translation unit needs it, keep it static and drop the header prototype to avoid unnecessarily expanding the driver’s internal API surface.

Suggested change
+void aq_nic_dim_update(struct aq_nic_s *self);

Copilot uses AI. Check for mistakes.
+
#endif /* AQ_NIC_H */
--- a/drivers/net/ethernet/aquantia/atlantic/aq_nic.c 2026-02-16 16:11:45.000000000 +0000
+++ b/drivers/net/ethernet/aquantia/atlantic/aq_nic.c 2026-02-23 01:33:44.071788263 +0000
@@ -18,6 +18,7 @@
#include "aq_ptp.h"
#include "aq_filters.h"

+#include <linux/dim.h>
#include <linux/moduleparam.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
@@ -65,6 +66,86 @@
rss_params->indirection_table[i] = i & (num_rss_queues - 1);
}

+/* ---- DIM (Dynamic Interrupt Moderation) ---- */
+
+static void aq_nic_rx_dim_work(struct work_struct *work)
+{
+ struct dim *dim = container_of(work, struct dim, work);
+ struct aq_nic_s *nic = container_of(dim, struct aq_nic_s, rx_dim);
+ struct dim_cq_moder moder;
+
+ moder = net_dim_get_rx_moderation(dim->mode, dim->profile_ix);
+
+ /* Clamp to hardware max (0x1FF * 2 = 1022 usec) */
+ if (moder.usec > AQ_CFG_INTERRUPT_MODERATION_USEC_MAX)
+ moder.usec = AQ_CFG_INTERRUPT_MODERATION_USEC_MAX;
+
+ nic->aq_nic_cfg.rx_itr = moder.usec;
+ nic->aq_nic_cfg.itr = AQ_CFG_INTERRUPT_MODERATION_ON;
+
+ aq_nic_update_interrupt_moderation_settings(nic);
+
+ dim->state = DIM_START_MEASURE;
+}
+
+static void aq_nic_tx_dim_work(struct work_struct *work)
+{
+ struct dim *dim = container_of(work, struct dim, work);
+ struct aq_nic_s *nic = container_of(dim, struct aq_nic_s, tx_dim);
+ struct dim_cq_moder moder;
+
+ moder = net_dim_get_tx_moderation(dim->mode, dim->profile_ix);
+
+ if (moder.usec > AQ_CFG_INTERRUPT_MODERATION_USEC_MAX)
+ moder.usec = AQ_CFG_INTERRUPT_MODERATION_USEC_MAX;
+
+ nic->aq_nic_cfg.tx_itr = moder.usec;
+ nic->aq_nic_cfg.itr = AQ_CFG_INTERRUPT_MODERATION_ON;
+
+ aq_nic_update_interrupt_moderation_settings(nic);
+
+ dim->state = DIM_START_MEASURE;
+}
+
+static void aq_nic_dim_init(struct aq_nic_s *self)
+{
+ INIT_WORK(&self->rx_dim.work, aq_nic_rx_dim_work);
+ self->rx_dim.mode = DIM_CQ_PERIOD_MODE_START_FROM_EQE;
+ self->rx_dim.profile_ix = 1; /* start at moderate profile */
+
+ INIT_WORK(&self->tx_dim.work, aq_nic_tx_dim_work);
+ self->tx_dim.mode = DIM_CQ_PERIOD_MODE_START_FROM_EQE;
+ self->tx_dim.profile_ix = 1;
+
+ self->dim_event_ctr = 0;
+}
+
+void aq_nic_dim_update(struct aq_nic_s *self)
+{
+ struct dim_sample sample = {};
+
+ self->dim_event_ctr++;
+
+ /* Use hardware-level DMA packet/byte counters for global view */
+ dim_update_sample(self->dim_event_ctr,
+ self->aq_hw->curr_stats.dma_pkt_rc,
+ self->aq_hw->curr_stats.dma_oct_rc,
+ &sample);
+
+ if (self->aq_nic_cfg.is_rx_adaptive)
+ net_dim(&self->rx_dim, &sample);
+
+ if (self->aq_nic_cfg.is_tx_adaptive) {
+ struct dim_sample tx_sample = {};
+
+ dim_update_sample(self->dim_event_ctr,
+ self->aq_hw->curr_stats.dma_pkt_tc,
+ self->aq_hw->curr_stats.dma_oct_tc,
+ &tx_sample);
+ net_dim(&self->tx_dim, &tx_sample);
+ }
+}
+
/* Recalculate the number of vectors */
static void aq_nic_cfg_update_num_vecs(struct aq_nic_s *self)
{
@@ -250,6 +331,11 @@
mutex_unlock(&self->fwreq_mutex);

aq_nic_update_ndev_stats(self);
+
+ /* Update DIM if adaptive coalescing is enabled */
+ if (self->aq_nic_cfg.is_rx_adaptive ||
+ self->aq_nic_cfg.is_tx_adaptive)
+ aq_nic_dim_update(self);
}

static void aq_nic_service_timer_cb(struct timer_list *t)
@@ -424,6 +510,8 @@
if (err < 0)
goto err_exit;

+ aq_nic_dim_init(self);
+
if (ATL_HW_IS_CHIP_FEATURE(self->aq_hw, ATLANTIC) &&
self->aq_nic_cfg.aq_hw_caps->media_type == AQ_HW_MEDIA_TYPE_TP) {
self->aq_hw->phy_id = HW_ATL_PHY_ID_MAX;
@@ -1432,6 +1520,12 @@
if (!self)
goto err_exit;

+ /* Cancel any pending DIM work before teardown */
+ cancel_work_sync(&self->rx_dim.work);
+ cancel_work_sync(&self->tx_dim.work);
+ self->aq_nic_cfg.is_rx_adaptive = false;
+ self->aq_nic_cfg.is_tx_adaptive = false;
+
for (i = 0U; i < self->aq_vecs; i++) {
aq_vec = self->aq_vec[i];
aq_vec_deinit(aq_vec);
--- a/drivers/net/ethernet/aquantia/atlantic/aq_ethtool.c 2026-02-16 16:11:45.000000000 +0000
+++ b/drivers/net/ethernet/aquantia/atlantic/aq_ethtool.c 2026-02-23 01:33:58.379663822 +0000
@@ -562,6 +562,9 @@

cfg = aq_nic_get_cfg(aq_nic);

+ coal->use_adaptive_rx_coalesce = cfg->is_rx_adaptive;
+ coal->use_adaptive_tx_coalesce = cfg->is_tx_adaptive;
+
if (cfg->itr == AQ_CFG_INTERRUPT_MODERATION_ON ||
cfg->itr == AQ_CFG_INTERRUPT_MODERATION_AUTO) {
coal->rx_coalesce_usecs = cfg->rx_itr;
@@ -588,6 +591,23 @@

cfg = aq_nic_get_cfg(aq_nic);

+ /* Handle adaptive coalescing (DIM) mode */
+ cfg->is_rx_adaptive = !!coal->use_adaptive_rx_coalesce;
+ cfg->is_tx_adaptive = !!coal->use_adaptive_tx_coalesce;
+
+ if (cfg->is_rx_adaptive || cfg->is_tx_adaptive) {
+ /* Enable HW moderation engine; DIM manages the timers */
+ cfg->itr = AQ_CFG_INTERRUPT_MODERATION_ON;
+
+ /* Allow user to set initial timer values alongside adaptive */
+ if (coal->rx_coalesce_usecs)
+ cfg->rx_itr = coal->rx_coalesce_usecs;
+ if (coal->tx_coalesce_usecs)
+ cfg->tx_itr = coal->tx_coalesce_usecs;
+
+ return aq_nic_update_interrupt_moderation_settings(aq_nic);
+ }

Copilot AI Feb 24, 2026

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In the adaptive-coalesce branch, the early return aq_nic_update_interrupt_moderation_settings() bypasses the existing validation below (e.g., checks rejecting rx_max_coalesced_frames > 1, and any bounds checks for usecs). This can allow invalid/unsupported coalesce parameters to be accepted whenever adaptive mode is enabled. Keep the same parameter validation in place before returning (or replicate the relevant checks inside the adaptive branch).

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+
/* Atlantic only supports timing based coalescing
*/
if (coal->rx_max_coalesced_frames > 1 ||
@@ -1050,7 +1070,8 @@

const struct ethtool_ops aq_ethtool_ops = {
.supported_coalesce_params = ETHTOOL_COALESCE_USECS |
- ETHTOOL_COALESCE_MAX_FRAMES,
+ ETHTOOL_COALESCE_MAX_FRAMES |
+ ETHTOOL_COALESCE_USE_ADAPTIVE,
.get_link = aq_ethtool_get_link,
.get_regs_len = aq_ethtool_get_regs_len,
.get_regs = aq_ethtool_get_regs,
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