From: Kai-Heng Feng kai.heng.feng@canonical.com
[ Upstream commit 4e0effd9007ea0be31f7488611eb3824b4541554 ]
Intel I210 on some Intel Alder Lake platforms can only achieve ~750Mbps Tx speed via iperf. The RR2DCDELAY shows around 0x2xxx DMA delay, which will be significantly lower when 1) ASPM is disabled or 2) SoC package c-state stays above PC3. When the RR2DCDELAY is around 0x1xxx the Tx speed can reach to ~950Mbps.
According to the I210 datasheet "8.26.1 PCIe Misc. Register - PCIEMISC", "DMA Idle Indication" doesn't seem to tie to DMA coalesce anymore, so set it to 1b for "DMA is considered idle when there is no Rx or Tx AND when there are no TLPs indicating that CPU is active detected on the PCIe link (such as the host executes CSR or Configuration register read or write operation)" and performing Tx should also fall under "active CPU on PCIe link" case.
In addition to that, commit b6e0c419f040 ("igb: Move DMA Coalescing init code to separate function.") seems to wrongly changed from enabling E1000_PCIEMISC_LX_DECISION to disabling it, also fix that.
Fixes: b6e0c419f040 ("igb: Move DMA Coalescing init code to separate function.") Signed-off-by: Kai-Heng Feng kai.heng.feng@canonical.com Tested-by: Gurucharan gurucharanx.g@intel.com (A Contingent worker at Intel) Signed-off-by: Tony Nguyen anthony.l.nguyen@intel.com Link: https://lore.kernel.org/r/20220621221056.604304-1-anthony.l.nguyen@intel.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/intel/igb/igb_main.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-)
diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c index a93edd31011f..9f45ecd9e8e5 100644 --- a/drivers/net/ethernet/intel/igb/igb_main.c +++ b/drivers/net/ethernet/intel/igb/igb_main.c @@ -9444,11 +9444,10 @@ static void igb_init_dmac(struct igb_adapter *adapter, u32 pba) struct e1000_hw *hw = &adapter->hw; u32 dmac_thr; u16 hwm; + u32 reg;
if (hw->mac.type > e1000_82580) { if (adapter->flags & IGB_FLAG_DMAC) { - u32 reg; - /* force threshold to 0. */ wr32(E1000_DMCTXTH, 0);
@@ -9481,7 +9480,6 @@ static void igb_init_dmac(struct igb_adapter *adapter, u32 pba) /* Disable BMC-to-OS Watchdog Enable */ if (hw->mac.type != e1000_i354) reg &= ~E1000_DMACR_DC_BMC2OSW_EN; - wr32(E1000_DMACR, reg);
/* no lower threshold to disable @@ -9498,12 +9496,12 @@ static void igb_init_dmac(struct igb_adapter *adapter, u32 pba) */ wr32(E1000_DMCTXTH, (IGB_MIN_TXPBSIZE - (IGB_TX_BUF_4096 + adapter->max_frame_size)) >> 6); + }
- /* make low power state decision controlled - * by DMA coal - */ + if (hw->mac.type >= e1000_i210 || + (adapter->flags & IGB_FLAG_DMAC)) { reg = rd32(E1000_PCIEMISC); - reg &= ~E1000_PCIEMISC_LX_DECISION; + reg |= E1000_PCIEMISC_LX_DECISION; wr32(E1000_PCIEMISC, reg); } /* endif adapter->dmac is not disabled */ } else if (hw->mac.type == e1000_82580) {