This enables OSP (Operate on Second Packet) for GMAC4. The feature allows DMA to fetch second descriptor while its still processing the first one.
Running iperf, the performance gain is +/- 38%. Signed-off-by: Jose Abreu <[email protected]> Cc: David S. Miller <[email protected]> Cc: Joao Pinto <[email protected]> Cc: Vitor Soares <[email protected]> Cc: Giuseppe Cavallaro <[email protected]> Cc: Alexandre Torgue <[email protected]> --- drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-) diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c b/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c index 117c3a5..9aab5b3 100644 --- a/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c @@ -94,6 +94,10 @@ static void dwmac4_dma_init_tx_chan(void __iomem *ioaddr, value = readl(ioaddr + DMA_CHAN_TX_CONTROL(chan)); value = value | (txpbl << DMA_BUS_MODE_PBL_SHIFT); + + /* Enable OSP to get best performance */ + value |= DMA_CONTROL_OSP; + writel(value, ioaddr + DMA_CHAN_TX_CONTROL(chan)); writel(dma_tx_phy, ioaddr + DMA_CHAN_TX_BASE_ADDR(chan)); -- 1.7.1
