bnxt_en: Reorganize the coalescing parameters.

The current IRQ coalescing logic is a little messy.  The ethtool
parameters are mapped to hardware parameters in a way that is difficult
to understand.  The first step is to better organize the parameters
by adding the new structure bnxt_coal.  The structure is used by both
the RX and TX sets of coalescing parameters.

Adjust the default coal_ticks to 14 us and 28 us for RX and TX.
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -4569,34 +4569,31 @@ int bnxt_hwrm_set_coal(struct bnxt *bp)
 	/* Each rx completion (2 records) should be DMAed immediately.
 	 * DMA 1/4 of the completion buffers at a time.
 	 */
-	max_buf = min_t(u16, bp->rx_coal_bufs / 4, 2);
+	max_buf = min_t(u16, bp->rx_coal.coal_bufs / 4, 2);
 	/* max_buf must not be zero */
 	max_buf = clamp_t(u16, max_buf, 1, 63);
-	max_buf_irq = clamp_t(u16, bp->rx_coal_bufs_irq, 1, 63);
-	buf_tmr = BNXT_USEC_TO_COAL_TIMER(bp->rx_coal_ticks);
+	max_buf_irq = clamp_t(u16, bp->rx_coal.coal_bufs_irq, 1, 63);
+	buf_tmr = BNXT_USEC_TO_COAL_TIMER(bp->rx_coal.coal_ticks);
 	/* buf timer set to 1/4 of interrupt timer */
 	buf_tmr = max_t(u16, buf_tmr / 4, 1);
-	buf_tmr_irq = BNXT_USEC_TO_COAL_TIMER(bp->rx_coal_ticks_irq);
+	buf_tmr_irq = BNXT_USEC_TO_COAL_TIMER(bp->rx_coal.coal_ticks_irq);
 	buf_tmr_irq = max_t(u16, buf_tmr_irq, 1);
 
 	flags = RING_CMPL_RING_CFG_AGGINT_PARAMS_REQ_FLAGS_TIMER_RESET;
 
-	/* RING_IDLE generates more IRQs for lower latency.  Enable it only
-	 * if coal_ticks is less than 25 us.
-	 */
-	if (bp->rx_coal_ticks < 25)
+	if (bp->rx_coal.coal_ticks < bp->rx_coal.idle_thresh)
 		flags |= RING_CMPL_RING_CFG_AGGINT_PARAMS_REQ_FLAGS_RING_IDLE;
 
 	bnxt_hwrm_set_coal_params(bp, max_buf_irq << 16 | max_buf,
 				  buf_tmr_irq << 16 | buf_tmr, flags, &req_rx);
 
 	/* max_buf must not be zero */
-	max_buf = clamp_t(u16, bp->tx_coal_bufs, 1, 63);
-	max_buf_irq = clamp_t(u16, bp->tx_coal_bufs_irq, 1, 63);
-	buf_tmr = BNXT_USEC_TO_COAL_TIMER(bp->tx_coal_ticks);
+	max_buf = clamp_t(u16, bp->tx_coal.coal_bufs, 1, 63);
+	max_buf_irq = clamp_t(u16, bp->tx_coal.coal_bufs_irq, 1, 63);
+	buf_tmr = BNXT_USEC_TO_COAL_TIMER(bp->tx_coal.coal_ticks);
 	/* buf timer set to 1/4 of interrupt timer */
 	buf_tmr = max_t(u16, buf_tmr / 4, 1);
-	buf_tmr_irq = BNXT_USEC_TO_COAL_TIMER(bp->tx_coal_ticks_irq);
+	buf_tmr_irq = BNXT_USEC_TO_COAL_TIMER(bp->tx_coal.coal_ticks_irq);
 	buf_tmr_irq = max_t(u16, buf_tmr_irq, 1);
 
 	flags = RING_CMPL_RING_CFG_AGGINT_PARAMS_REQ_FLAGS_TIMER_RESET;
@@ -7146,6 +7143,32 @@ static void bnxt_cleanup_pci(struct bnxt *bp)
 	pci_disable_device(bp->pdev);
 }
 
+static void bnxt_init_dflt_coal(struct bnxt *bp)
+{
+	struct bnxt_coal *coal;
+
+	/* Tick values in micro seconds.
+	 * 1 coal_buf x bufs_per_record = 1 completion record.
+	 */
+	coal = &bp->rx_coal;
+	coal->coal_ticks = 14;
+	coal->coal_bufs = 30;
+	coal->coal_ticks_irq = 1;
+	coal->coal_bufs_irq = 2;
+	coal->idle_thresh = 25;
+	coal->bufs_per_record = 2;
+	coal->budget = 64;		/* NAPI budget */
+
+	coal = &bp->tx_coal;
+	coal->coal_ticks = 28;
+	coal->coal_bufs = 30;
+	coal->coal_ticks_irq = 2;
+	coal->coal_bufs_irq = 2;
+	coal->bufs_per_record = 1;
+
+	bp->stats_coal_ticks = BNXT_DEF_STATS_COAL_TICKS;
+}
+
 static int bnxt_init_board(struct pci_dev *pdev, struct net_device *dev)
 {
 	int rc;
@@ -7214,18 +7237,7 @@ static int bnxt_init_board(struct pci_dev *pdev, struct net_device *dev)
 	bp->rx_ring_size = BNXT_DEFAULT_RX_RING_SIZE;
 	bp->tx_ring_size = BNXT_DEFAULT_TX_RING_SIZE;
 
-	/* tick values in micro seconds */
-	bp->rx_coal_ticks = 12;
-	bp->rx_coal_bufs = 30;
-	bp->rx_coal_ticks_irq = 1;
-	bp->rx_coal_bufs_irq = 2;
-
-	bp->tx_coal_ticks = 25;
-	bp->tx_coal_bufs = 30;
-	bp->tx_coal_ticks_irq = 2;
-	bp->tx_coal_bufs_irq = 2;
-
-	bp->stats_coal_ticks = BNXT_DEF_STATS_COAL_TICKS;
+	bnxt_init_dflt_coal(bp);
 
 	setup_timer(&bp->timer, bnxt_timer, (unsigned long)bp);
 	bp->current_interval = BNXT_TIMER_INTERVAL;

drivers/net/ethernet/broadcom/bnxt/bnxt.h

@@ -944,6 +944,17 @@ struct bnxt_test_info {
 #define BNXT_CAG_REG_LEGACY_INT_STATUS	0x4014
 #define BNXT_CAG_REG_BASE		0x300000
 
+struct bnxt_coal {
+	u16			coal_ticks;
+	u16			coal_ticks_irq;
+	u16			coal_bufs;
+	u16			coal_bufs_irq;
+			/* RING_IDLE enabled when coal ticks < idle_thresh  */
+	u16			idle_thresh;
+	u8			bufs_per_record;
+	u8			budget;
+};
+
 struct bnxt_tc_info {
 	bool				enabled;
 
@@ -1235,14 +1246,8 @@ struct bnxt {
 	u8			port_count;
 	u16			br_mode;
 
-	u16			rx_coal_ticks;
-	u16			rx_coal_ticks_irq;
-	u16			rx_coal_bufs;
-	u16			rx_coal_bufs_irq;
-	u16			tx_coal_ticks;
-	u16			tx_coal_ticks_irq;
-	u16			tx_coal_bufs;
-	u16			tx_coal_bufs_irq;
+	struct bnxt_coal	rx_coal;
+	struct bnxt_coal	tx_coal;
 
 #define BNXT_USEC_TO_COAL_TIMER(x)	((x) * 25 / 2)
 

drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c

@@ -44,19 +44,24 @@ static int bnxt_get_coalesce(struct net_device *dev,
 			     struct ethtool_coalesce *coal)
 {
 	struct bnxt *bp = netdev_priv(dev);
+	struct bnxt_coal *hw_coal;
+	u16 mult;
 
 	memset(coal, 0, sizeof(*coal));
 
-	coal->rx_coalesce_usecs = bp->rx_coal_ticks;
-	/* 2 completion records per rx packet */
-	coal->rx_max_coalesced_frames = bp->rx_coal_bufs / 2;
-	coal->rx_coalesce_usecs_irq = bp->rx_coal_ticks_irq;
-	coal->rx_max_coalesced_frames_irq = bp->rx_coal_bufs_irq / 2;
+	hw_coal = &bp->rx_coal;
+	mult = hw_coal->bufs_per_record;
+	coal->rx_coalesce_usecs = hw_coal->coal_ticks;
+	coal->rx_max_coalesced_frames = hw_coal->coal_bufs / mult;
+	coal->rx_coalesce_usecs_irq = hw_coal->coal_ticks_irq;
+	coal->rx_max_coalesced_frames_irq = hw_coal->coal_bufs_irq / mult;
 
-	coal->tx_coalesce_usecs = bp->tx_coal_ticks;
-	coal->tx_max_coalesced_frames = bp->tx_coal_bufs;
-	coal->tx_coalesce_usecs_irq = bp->tx_coal_ticks_irq;
-	coal->tx_max_coalesced_frames_irq = bp->tx_coal_bufs_irq;
+	hw_coal = &bp->tx_coal;
+	mult = hw_coal->bufs_per_record;
+	coal->tx_coalesce_usecs = hw_coal->coal_ticks;
+	coal->tx_max_coalesced_frames = hw_coal->coal_bufs / mult;
+	coal->tx_coalesce_usecs_irq = hw_coal->coal_ticks_irq;
+	coal->tx_max_coalesced_frames_irq = hw_coal->coal_bufs_irq / mult;
 
 	coal->stats_block_coalesce_usecs = bp->stats_coal_ticks;
 
@@ -68,18 +73,23 @@ static int bnxt_set_coalesce(struct net_device *dev,
 {
 	struct bnxt *bp = netdev_priv(dev);
 	bool update_stats = false;
+	struct bnxt_coal *hw_coal;
 	int rc = 0;
-
-	bp->rx_coal_ticks = coal->rx_coalesce_usecs;
-	/* 2 completion records per rx packet */
-	bp->rx_coal_bufs = coal->rx_max_coalesced_frames * 2;
-	bp->rx_coal_ticks_irq = coal->rx_coalesce_usecs_irq;
-	bp->rx_coal_bufs_irq = coal->rx_max_coalesced_frames_irq * 2;
-
-	bp->tx_coal_ticks = coal->tx_coalesce_usecs;
-	bp->tx_coal_bufs = coal->tx_max_coalesced_frames;
-	bp->tx_coal_ticks_irq = coal->tx_coalesce_usecs_irq;
-	bp->tx_coal_bufs_irq = coal->tx_max_coalesced_frames_irq;
+	u16 mult;
+
+	hw_coal = &bp->rx_coal;
+	mult = hw_coal->bufs_per_record;
+	hw_coal->coal_ticks = coal->rx_coalesce_usecs;
+	hw_coal->coal_bufs = coal->rx_max_coalesced_frames * mult;
+	hw_coal->coal_ticks_irq = coal->rx_coalesce_usecs_irq;
+	hw_coal->coal_bufs_irq = coal->rx_max_coalesced_frames_irq * mult;
+
+	hw_coal = &bp->rx_coal;
+	mult = hw_coal->bufs_per_record;
+	hw_coal->coal_ticks = coal->tx_coalesce_usecs;
+	hw_coal->coal_bufs = coal->tx_max_coalesced_frames * mult;
+	hw_coal->coal_ticks_irq = coal->tx_coalesce_usecs_irq;
+	hw_coal->coal_bufs_irq = coal->tx_max_coalesced_frames_irq * mult;
 
 	if (bp->stats_coal_ticks != coal->stats_block_coalesce_usecs) {
 		u32 stats_ticks = coal->stats_block_coalesce_usecs;