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igb: Add DMA Coalescing feature to driver 

This patch add DMA Coalescing which is a power-saving feature that
coalesces DMA writes in order to stay in a low-power state as much
as possible.  Feature is disabled by default.

Signed-off-by: Carolyn Wyborny <carolyn.wyborny@intel.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
This commit is contained in:
Carolyn Wyborny 2011-03-11 20:43:54 -08:00 committed by Jeff Kirsher
parent 4322e561a9
commit 831ec0b422
5 changed files with 106 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
drivers/net/igb/e1000_defines.h
View File

@ -287,7 +287,34 @@
#define E1000_TCTL_COLD 0x003ff000 /* collision distance */
#define E1000_TCTL_RTLC 0x01000000 /* Re-transmit on late collision */
/* Transmit Arbitration Count */
/* DMA Coalescing register fields */
#define E1000_DMACR_DMACWT_MASK 0x00003FFF /* DMA Coalescing
* Watchdog Timer */
#define E1000_DMACR_DMACTHR_MASK 0x00FF0000 /* DMA Coalescing Receive
* Threshold */
#define E1000_DMACR_DMACTHR_SHIFT 16
#define E1000_DMACR_DMAC_LX_MASK 0x30000000 /* Lx when no PCIe
* transactions */
#define E1000_DMACR_DMAC_LX_SHIFT 28
#define E1000_DMACR_DMAC_EN 0x80000000 /* Enable DMA Coalescing */
#define E1000_DMCTXTH_DMCTTHR_MASK 0x00000FFF /* DMA Coalescing Transmit
* Threshold */
#define E1000_DMCTLX_TTLX_MASK 0x00000FFF /* Time to LX request */
#define E1000_DMCRTRH_UTRESH_MASK 0x0007FFFF /* Receive Traffic Rate
* Threshold */
#define E1000_DMCRTRH_LRPRCW 0x80000000 /* Rcv packet rate in
* current window */
#define E1000_DMCCNT_CCOUNT_MASK 0x01FFFFFF /* DMA Coal Rcv Traffic
* Current Cnt */
#define E1000_FCRTC_RTH_COAL_MASK 0x0003FFF0 /* Flow ctrl Rcv Threshold
* High val */
#define E1000_FCRTC_RTH_COAL_SHIFT 4
#define E1000_PCIEMISC_LX_DECISION 0x00000080 /* Lx power decision */
/* SerDes Control */
#define E1000_SCTL_DISABLE_SERDES_LOOPBACK 0x0400

9
drivers/net/igb/e1000_regs.h
View File

@ -106,6 +106,15 @@
#define E1000_RQDPC(_n) (0x0C030 + ((_n) * 0x40))
/* DMA Coalescing registers */
#define E1000_DMACR 0x02508 /* Control Register */
#define E1000_DMCTXTH 0x03550 /* Transmit Threshold */
#define E1000_DMCTLX 0x02514 /* Time to Lx Request */
#define E1000_DMCRTRH 0x05DD0 /* Receive Packet Rate Threshold */
#define E1000_DMCCNT 0x05DD4 /* Current Rx Count */
#define E1000_FCRTC 0x02170 /* Flow Control Rx high watermark */
#define E1000_PCIEMISC 0x05BB8 /* PCIE misc config register */
/* TX Rate Limit Registers */
#define E1000_RTTDQSEL 0x3604 /* Tx Desc Plane Queue Select - WO */
#define E1000_RTTBCNRC 0x36B0 /* Tx BCN Rate-Scheduler Config - WO */

6
drivers/net/igb/igb.h
View File

@ -333,6 +333,12 @@ struct igb_adapter {
#define IGB_FLAG_DCA_ENABLED (1 << 1)
#define IGB_FLAG_QUAD_PORT_A (1 << 2)
#define IGB_FLAG_QUEUE_PAIRS (1 << 3)
#define IGB_FLAG_DMAC (1 << 4)
/* DMA Coalescing defines */
#define IGB_MIN_TXPBSIZE 20408
#define IGB_TX_BUF_4096 4096
#define IGB_DMCTLX_DCFLUSH_DIS 0x80000000 /* Disable DMA Coal Flush */
#define IGB_82576_TSYNC_SHIFT 19
#define IGB_82580_TSYNC_SHIFT 24

6
drivers/net/igb/igb_ethtool.c
View File

@ -2009,6 +2009,12 @@ static int igb_set_coalesce(struct net_device *netdev,
if ((adapter->flags & IGB_FLAG_QUEUE_PAIRS) && ec->tx_coalesce_usecs)
return -EINVAL;
/* If ITR is disabled, disable DMAC */
if (ec->rx_coalesce_usecs == 0) {
if (adapter->flags & IGB_FLAG_DMAC)
adapter->flags &= ~IGB_FLAG_DMAC;
}
/* convert to rate of irq's per second */
if (ec->rx_coalesce_usecs && ec->rx_coalesce_usecs <= 3)
adapter->rx_itr_setting = ec->rx_coalesce_usecs;

57
drivers/net/igb/igb_main.c
View File

@ -1674,7 +1674,58 @@ void igb_reset(struct igb_adapter *adapter)
if (hw->mac.ops.init_hw(hw))
dev_err(&pdev->dev, "Hardware Error\n");
if (hw->mac.type > e1000_82580) {
if (adapter->flags & IGB_FLAG_DMAC) {
u32 reg;
/*
* DMA Coalescing high water mark needs to be higher
* than * the * Rx threshold. The Rx threshold is
* currently * pba - 6, so we * should use a high water
* mark of pba * - 4. */
hwm = (pba - 4) << 10;
reg = (((pba-6) << E1000_DMACR_DMACTHR_SHIFT)
& E1000_DMACR_DMACTHR_MASK);
/* transition to L0x or L1 if available..*/
reg |= (E1000_DMACR_DMAC_EN | E1000_DMACR_DMAC_LX_MASK);
/* watchdog timer= +-1000 usec in 32usec intervals */
reg |= (1000 >> 5);
wr32(E1000_DMACR, reg);
/* no lower threshold to disable coalescing(smart fifb)
* -UTRESH=0*/
wr32(E1000_DMCRTRH, 0);
/* set hwm to PBA - 2 * max frame size */
wr32(E1000_FCRTC, hwm);
/*
* This sets the time to wait before requesting tran-
* sition to * low power state to number of usecs needed
* to receive 1 512 * byte frame at gigabit line rate
*/
reg = rd32(E1000_DMCTLX);
reg |= IGB_DMCTLX_DCFLUSH_DIS;
/* Delay 255 usec before entering Lx state. */
reg |= 0xFF;
wr32(E1000_DMCTLX, reg);
/* free space in Tx packet buffer to wake from DMAC */
wr32(E1000_DMCTXTH,
(IGB_MIN_TXPBSIZE -
(IGB_TX_BUF_4096 + adapter->max_frame_size))
>> 6);
/* make low power state decision controlled by DMAC */
reg = rd32(E1000_PCIEMISC);
reg |= E1000_PCIEMISC_LX_DECISION;
wr32(E1000_PCIEMISC, reg);
} /* end if IGB_FLAG_DMAC set */
}
if (hw->mac.type == e1000_82580) {
u32 reg = rd32(E1000_PCIEMISC);
wr32(E1000_PCIEMISC,
@ -2157,6 +2208,9 @@ static void __devinit igb_probe_vfs(struct igb_adapter * adapter)
random_ether_addr(mac_addr);
igb_set_vf_mac(adapter, i, mac_addr);
}
/* DMA Coalescing is not supported in IOV mode. */
if (adapter->flags & IGB_FLAG_DMAC)
adapter->flags &= ~IGB_FLAG_DMAC;
}
#endif /* CONFIG_PCI_IOV */
}
@ -2331,6 +2385,9 @@ static int __devinit igb_sw_init(struct igb_adapter *adapter)
/* Explicitly disable IRQ since the NIC can be in any state. */
igb_irq_disable(adapter);
if (hw->mac.type == e1000_i350)
adapter->flags &= ~IGB_FLAG_DMAC;
set_bit(__IGB_DOWN, &adapter->state);
return 0;
}