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Date: Fri, 4 Mar 2022 23:01:19 +0000
From: Robert Hancock <robert.hancock@...ian.com>
To: "netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC: "linux@...linux.org.uk" <linux@...linux.org.uk>,
"davem@...emloft.net" <davem@...emloft.net>,
"kuba@...nel.org" <kuba@...nel.org>,
"michal.simek@...inx.com" <michal.simek@...inx.com>,
"radhey.shyam.pandey@...inx.com" <radhey.shyam.pandey@...inx.com>,
"daniel@...earbox.net" <daniel@...earbox.net>
Subject: Re: [PATCH net-next 7/7] net: axienet: add coalesce timer ethtool
configuration
On Fri, 2022-03-04 at 16:42 -0600, Robert Hancock wrote:
> Add the ability to configure the RX/TX coalesce timer with ethtool.
> Change default setting to scale with the clock rate rather than being a
> fixed number of clock cycles.
>
> Signed-off-by: Robert Hancock <robert.hancock@...ian.com>
> ---
> drivers/net/ethernet/xilinx/xilinx_axienet.h | 8 +--
> .../net/ethernet/xilinx/xilinx_axienet_main.c | 49 +++++++++++++++----
> 2 files changed, 44 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet.h
> b/drivers/net/ethernet/xilinx/xilinx_axienet.h
> index 6f0f13b4fb1a..f6d365cb57de 100644
> --- a/drivers/net/ethernet/xilinx/xilinx_axienet.h
> +++ b/drivers/net/ethernet/xilinx/xilinx_axienet.h
> @@ -119,11 +119,11 @@
> #define XAXIDMA_IRQ_ERROR_MASK 0x00004000 /* Error interrupt
> */
> #define XAXIDMA_IRQ_ALL_MASK 0x00007000 /* All interrupts */
>
> -/* Default TX/RX Threshold and waitbound values for SGDMA mode */
> +/* Default TX/RX Threshold and delay timer values for SGDMA mode */
> #define XAXIDMA_DFT_TX_THRESHOLD 24
> -#define XAXIDMA_DFT_TX_WAITBOUND 254
> +#define XAXIDMA_DFT_TX_USEC 50
> #define XAXIDMA_DFT_RX_THRESHOLD 1
> -#define XAXIDMA_DFT_RX_WAITBOUND 254
> +#define XAXIDMA_DFT_RX_USEC 50
>
> #define XAXIDMA_BD_CTRL_TXSOF_MASK 0x08000000 /* First tx packet */
> #define XAXIDMA_BD_CTRL_TXEOF_MASK 0x04000000 /* Last tx packet */
> @@ -482,7 +482,9 @@ struct axienet_local {
> int csum_offload_on_rx_path;
>
> u32 coalesce_count_rx;
> + u32 coalesce_usec_rx;
> u32 coalesce_count_tx;
> + u32 coalesce_usec_tx;
> };
>
> /**
> diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
> b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
> index 828ab7a81797..8d908a5feea2 100644
> --- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
> +++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
> @@ -226,6 +226,28 @@ static void axienet_dma_bd_release(struct net_device
> *ndev)
> lp->rx_bd_p);
> }
>
> +/**
> + * axienet_usec_to_timer - Calculate IRQ delay timer value
> + * @lp: Pointer to the axienet_local structure
> + * @coalesce_usec: Microseconds to convert into timer value
> + */
> +static u32 axienet_usec_to_timer(struct axienet_local *lp, u32
> coalesce_usec)
> +{
> + u32 result;
> + u64 clk_rate = 125000000; /* arbitrary guess if no clock rate set */
> +
> + if (lp->axi_clk)
> + clk_rate = clk_get_rate(lp->axi_clk);
> +
> + /* 1 Timeout Interval = 125 * (clock period of SG clock) */
> + result = DIV_ROUND_CLOSEST((u64)coalesce_usec * clk_rate,
> + (u64)125000000);
Looks like there's a compile error on 32-bit here. Will fix..
> + if (result > 255)
> + result = 255;
> +
> + return result;
> +}
> +
> /**
> * axienet_dma_start - Set up DMA registers and start DMA operation
> * @lp: Pointer to the axienet_local structure
> @@ -241,7 +263,8 @@ static void axienet_dma_start(struct axienet_local *lp)
> * the first RX packet. Otherwise leave at 0 to disable delay
> interrupt.
> */
> if (lp->coalesce_count_rx > 1)
> - lp->rx_dma_cr |= (XAXIDMA_DFT_RX_WAITBOUND <<
> XAXIDMA_DELAY_SHIFT) |
> + lp->rx_dma_cr |= (axienet_usec_to_timer(lp, lp-
> >coalesce_usec_rx)
> + << XAXIDMA_DELAY_SHIFT) |
> XAXIDMA_IRQ_DELAY_MASK;
> axienet_dma_out32(lp, XAXIDMA_RX_CR_OFFSET, lp->rx_dma_cr);
>
> @@ -252,7 +275,8 @@ static void axienet_dma_start(struct axienet_local *lp)
> * the first TX packet. Otherwise leave at 0 to disable delay
> interrupt.
> */
> if (lp->coalesce_count_tx > 1)
> - tx_cr |= (XAXIDMA_DFT_TX_WAITBOUND << XAXIDMA_DELAY_SHIFT) |
> + tx_cr |= (axienet_usec_to_timer(lp, lp->coalesce_usec_tx)
> + << XAXIDMA_DELAY_SHIFT) |
> XAXIDMA_IRQ_DELAY_MASK;
> axienet_dma_out32(lp, XAXIDMA_TX_CR_OFFSET, tx_cr);
>
> @@ -1487,14 +1511,12 @@ axienet_ethtools_get_coalesce(struct net_device
> *ndev,
> struct kernel_ethtool_coalesce *kernel_coal,
> struct netlink_ext_ack *extack)
> {
> - u32 regval = 0;
> struct axienet_local *lp = netdev_priv(ndev);
> - regval = axienet_dma_in32(lp, XAXIDMA_RX_CR_OFFSET);
> - ecoalesce->rx_max_coalesced_frames = (regval & XAXIDMA_COALESCE_MASK)
> - >> XAXIDMA_COALESCE_SHIFT;
> - regval = axienet_dma_in32(lp, XAXIDMA_TX_CR_OFFSET);
> - ecoalesce->tx_max_coalesced_frames = (regval & XAXIDMA_COALESCE_MASK)
> - >> XAXIDMA_COALESCE_SHIFT;
> +
> + ecoalesce->rx_max_coalesced_frames = lp->coalesce_count_rx;
> + ecoalesce->rx_coalesce_usecs = lp->coalesce_usec_rx;
> + ecoalesce->tx_max_coalesced_frames = lp->coalesce_count_tx;
> + ecoalesce->tx_coalesce_usecs = lp->coalesce_usec_tx;
> return 0;
> }
>
> @@ -1527,8 +1549,12 @@ axienet_ethtools_set_coalesce(struct net_device *ndev,
>
> if (ecoalesce->rx_max_coalesced_frames)
> lp->coalesce_count_rx = ecoalesce->rx_max_coalesced_frames;
> + if (ecoalesce->rx_coalesce_usecs)
> + lp->coalesce_usec_rx = ecoalesce->rx_coalesce_usecs;
> if (ecoalesce->tx_max_coalesced_frames)
> lp->coalesce_count_tx = ecoalesce->tx_max_coalesced_frames;
> + if (ecoalesce->tx_coalesce_usecs)
> + lp->coalesce_usec_tx = ecoalesce->tx_coalesce_usecs;
>
> return 0;
> }
> @@ -1559,7 +1585,8 @@ static int axienet_ethtools_nway_reset(struct
> net_device *dev)
> }
>
> static const struct ethtool_ops axienet_ethtool_ops = {
> - .supported_coalesce_params = ETHTOOL_COALESCE_MAX_FRAMES,
> + .supported_coalesce_params = ETHTOOL_COALESCE_MAX_FRAMES |
> + ETHTOOL_COALESCE_USECS,
> .get_drvinfo = axienet_ethtools_get_drvinfo,
> .get_regs_len = axienet_ethtools_get_regs_len,
> .get_regs = axienet_ethtools_get_regs,
> @@ -2046,7 +2073,9 @@ static int axienet_probe(struct platform_device *pdev)
> }
>
> lp->coalesce_count_rx = XAXIDMA_DFT_RX_THRESHOLD;
> + lp->coalesce_usec_rx = XAXIDMA_DFT_RX_USEC;
> lp->coalesce_count_tx = XAXIDMA_DFT_TX_THRESHOLD;
> + lp->coalesce_usec_tx = XAXIDMA_DFT_TX_USEC;
>
> /* Reset core now that clocks are enabled, prior to accessing MDIO */
> ret = __axienet_device_reset(lp);
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