From 29ae6bd1b0d8a57d7c00ab12cbb949fc41986eef Mon Sep 17 00:00:00 2001 From: Andrew Lunn Date: Mon, 20 Apr 2020 00:04:00 +0200 Subject: [PATCH 1/3] net: ethernet: fec: Replace interrupt driven MDIO with polled IO Measurements of the MDIO bus have shown that driving the MDIO bus using interrupts is slow. Back to back MDIO transactions take about 90us, with 25us spent performing the transaction, and the remainder of the time the bus is idle. Replacing the completion interrupt with polled IO results in back to back transactions of 40us. The polling loop waiting for the hardware to complete the transaction takes around 28us. Which suggests interrupt handling has an overhead of 50us, and polled IO nearly halves this overhead, and doubles the MDIO performance. Suggested-by: Chris Heally Signed-off-by: Andrew Lunn Signed-off-by: David S. Miller --- drivers/net/ethernet/freescale/fec.h | 4 +- drivers/net/ethernet/freescale/fec_main.c | 67 ++++++++++++----------- 2 files changed, 35 insertions(+), 36 deletions(-) diff --git a/drivers/net/ethernet/freescale/fec.h b/drivers/net/ethernet/freescale/fec.h index e74dd1f86bba..a6cdd5b61921 100644 --- a/drivers/net/ethernet/freescale/fec.h +++ b/drivers/net/ethernet/freescale/fec.h @@ -376,8 +376,7 @@ struct bufdesc_ex { #define FEC_ENET_TS_AVAIL ((uint)0x00010000) #define FEC_ENET_TS_TIMER ((uint)0x00008000) -#define FEC_DEFAULT_IMASK (FEC_ENET_TXF | FEC_ENET_RXF | FEC_ENET_MII) -#define FEC_NAPI_IMASK FEC_ENET_MII +#define FEC_DEFAULT_IMASK (FEC_ENET_TXF | FEC_ENET_RXF) #define FEC_RX_DISABLED_IMASK (FEC_DEFAULT_IMASK & (~FEC_ENET_RXF)) /* ENET interrupt coalescing macro define */ @@ -543,7 +542,6 @@ struct fec_enet_private { int link; int full_duplex; int speed; - struct completion mdio_done; int irq[FEC_IRQ_NUM]; bool bufdesc_ex; int pause_flag; diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c index dc6f8763a5d4..2267bf75784e 100644 --- a/drivers/net/ethernet/freescale/fec_main.c +++ b/drivers/net/ethernet/freescale/fec_main.c @@ -976,8 +976,8 @@ fec_restart(struct net_device *ndev) writel((__force u32)cpu_to_be32(temp_mac[1]), fep->hwp + FEC_ADDR_HIGH); - /* Clear any outstanding interrupt. */ - writel(0xffffffff, fep->hwp + FEC_IEVENT); + /* Clear any outstanding interrupt, except MDIO. */ + writel((0xffffffff & ~FEC_ENET_MII), fep->hwp + FEC_IEVENT); fec_enet_bd_init(ndev); @@ -1123,7 +1123,7 @@ fec_restart(struct net_device *ndev) if (fep->link) writel(FEC_DEFAULT_IMASK, fep->hwp + FEC_IMASK); else - writel(FEC_ENET_MII, fep->hwp + FEC_IMASK); + writel(0, fep->hwp + FEC_IMASK); /* Init the interrupt coalescing */ fec_enet_itr_coal_init(ndev); @@ -1652,6 +1652,10 @@ fec_enet_interrupt(int irq, void *dev_id) irqreturn_t ret = IRQ_NONE; int_events = readl(fep->hwp + FEC_IEVENT); + + /* Don't clear MDIO events, we poll for those */ + int_events &= ~FEC_ENET_MII; + writel(int_events, fep->hwp + FEC_IEVENT); fec_enet_collect_events(fep, int_events); @@ -1659,16 +1663,12 @@ fec_enet_interrupt(int irq, void *dev_id) ret = IRQ_HANDLED; if (napi_schedule_prep(&fep->napi)) { - /* Disable the NAPI interrupts */ - writel(FEC_NAPI_IMASK, fep->hwp + FEC_IMASK); + /* Disable interrupts */ + writel(0, fep->hwp + FEC_IMASK); __napi_schedule(&fep->napi); } } - if (int_events & FEC_ENET_MII) { - ret = IRQ_HANDLED; - complete(&fep->mdio_done); - } return ret; } @@ -1818,11 +1818,24 @@ static void fec_enet_adjust_link(struct net_device *ndev) phy_print_status(phy_dev); } +static int fec_enet_mdio_wait(struct fec_enet_private *fep) +{ + uint ievent; + int ret; + + ret = readl_poll_timeout_atomic(fep->hwp + FEC_IEVENT, ievent, + ievent & FEC_ENET_MII, 2, 30000); + + if (!ret) + writel(FEC_ENET_MII, fep->hwp + FEC_IEVENT); + + return ret; +} + static int fec_enet_mdio_read(struct mii_bus *bus, int mii_id, int regnum) { struct fec_enet_private *fep = bus->priv; struct device *dev = &fep->pdev->dev; - unsigned long time_left; int ret = 0, frame_start, frame_addr, frame_op; bool is_c45 = !!(regnum & MII_ADDR_C45); @@ -1830,8 +1843,6 @@ static int fec_enet_mdio_read(struct mii_bus *bus, int mii_id, int regnum) if (ret < 0) return ret; - reinit_completion(&fep->mdio_done); - if (is_c45) { frame_start = FEC_MMFR_ST_C45; @@ -1843,11 +1854,9 @@ static int fec_enet_mdio_read(struct mii_bus *bus, int mii_id, int regnum) fep->hwp + FEC_MII_DATA); /* wait for end of transfer */ - time_left = wait_for_completion_timeout(&fep->mdio_done, - usecs_to_jiffies(FEC_MII_TIMEOUT)); - if (time_left == 0) { + ret = fec_enet_mdio_wait(fep); + if (ret) { netdev_err(fep->netdev, "MDIO address write timeout\n"); - ret = -ETIMEDOUT; goto out; } @@ -1866,11 +1875,9 @@ static int fec_enet_mdio_read(struct mii_bus *bus, int mii_id, int regnum) FEC_MMFR_TA, fep->hwp + FEC_MII_DATA); /* wait for end of transfer */ - time_left = wait_for_completion_timeout(&fep->mdio_done, - usecs_to_jiffies(FEC_MII_TIMEOUT)); - if (time_left == 0) { + ret = fec_enet_mdio_wait(fep); + if (ret) { netdev_err(fep->netdev, "MDIO read timeout\n"); - ret = -ETIMEDOUT; goto out; } @@ -1888,7 +1895,6 @@ static int fec_enet_mdio_write(struct mii_bus *bus, int mii_id, int regnum, { struct fec_enet_private *fep = bus->priv; struct device *dev = &fep->pdev->dev; - unsigned long time_left; int ret, frame_start, frame_addr; bool is_c45 = !!(regnum & MII_ADDR_C45); @@ -1898,8 +1904,6 @@ static int fec_enet_mdio_write(struct mii_bus *bus, int mii_id, int regnum, else ret = 0; - reinit_completion(&fep->mdio_done); - if (is_c45) { frame_start = FEC_MMFR_ST_C45; @@ -1911,11 +1915,9 @@ static int fec_enet_mdio_write(struct mii_bus *bus, int mii_id, int regnum, fep->hwp + FEC_MII_DATA); /* wait for end of transfer */ - time_left = wait_for_completion_timeout(&fep->mdio_done, - usecs_to_jiffies(FEC_MII_TIMEOUT)); - if (time_left == 0) { + ret = fec_enet_mdio_wait(fep); + if (ret) { netdev_err(fep->netdev, "MDIO address write timeout\n"); - ret = -ETIMEDOUT; goto out; } } else { @@ -1931,12 +1933,9 @@ static int fec_enet_mdio_write(struct mii_bus *bus, int mii_id, int regnum, fep->hwp + FEC_MII_DATA); /* wait for end of transfer */ - time_left = wait_for_completion_timeout(&fep->mdio_done, - usecs_to_jiffies(FEC_MII_TIMEOUT)); - if (time_left == 0) { + ret = fec_enet_mdio_wait(fep); + if (ret) netdev_err(fep->netdev, "MDIO write timeout\n"); - ret = -ETIMEDOUT; - } out: pm_runtime_mark_last_busy(dev); @@ -2132,6 +2131,9 @@ static int fec_enet_mii_init(struct platform_device *pdev) writel(fep->phy_speed, fep->hwp + FEC_MII_SPEED); + /* Clear any pending transaction complete indication */ + writel(FEC_ENET_MII, fep->hwp + FEC_IEVENT); + fep->mii_bus = mdiobus_alloc(); if (fep->mii_bus == NULL) { err = -ENOMEM; @@ -3674,7 +3676,6 @@ fec_probe(struct platform_device *pdev) fep->irq[i] = irq; } - init_completion(&fep->mdio_done); ret = fec_enet_mii_init(pdev); if (ret) goto failed_mii_init; From 3e782985cb3ce00a32c372b37d8feefdae18ddf1 Mon Sep 17 00:00:00 2001 From: Andrew Lunn Date: Mon, 20 Apr 2020 00:04:01 +0200 Subject: [PATCH 2/3] net: ethernet: fec: Allow configuration of MDIO bus speed MDIO busses typically operate at 2.5MHz. However many devices can operate at faster speeds. This then allows more MDIO transactions per second, useful for Ethernet switch statistics, or Ethernet PHY TDR data. Allow the bus speed to be configured, using the standard "clock-frequency" property, which i2c busses use to indicate the bus speed. Before using this property, ensure all devices on the bus do actually support the requested clock speed. Suggested-by: Chris Healy Signed-off-by: Andrew Lunn Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller --- Documentation/devicetree/bindings/net/fsl-fec.txt | 1 + Documentation/devicetree/bindings/net/mdio.yaml | 6 ++++++ drivers/net/ethernet/freescale/fec_main.c | 11 ++++++++--- 3 files changed, 15 insertions(+), 3 deletions(-) diff --git a/Documentation/devicetree/bindings/net/fsl-fec.txt b/Documentation/devicetree/bindings/net/fsl-fec.txt index ff8b0f211aa1..26c492a2e0e1 100644 --- a/Documentation/devicetree/bindings/net/fsl-fec.txt +++ b/Documentation/devicetree/bindings/net/fsl-fec.txt @@ -82,6 +82,7 @@ ethernet@83fec000 { phy-supply = <®_fec_supply>; phy-handle = <ðphy>; mdio { + clock-frequency = <5000000>; ethphy: ethernet-phy@6 { compatible = "ethernet-phy-ieee802.3-c22"; reg = <6>; diff --git a/Documentation/devicetree/bindings/net/mdio.yaml b/Documentation/devicetree/bindings/net/mdio.yaml index 50c3397a82bc..ab4a9df8b8e2 100644 --- a/Documentation/devicetree/bindings/net/mdio.yaml +++ b/Documentation/devicetree/bindings/net/mdio.yaml @@ -39,6 +39,12 @@ properties: and must therefore be appropriately determined based on all PHY requirements (maximum value of all per-PHY RESET pulse widths). + clock-frequency: + description: + Desired MDIO bus clock frequency in Hz. Values greater than IEEE 802.3 + defined 2.5MHz should only be used when all devices on the bus support + the given clock speed. + patternProperties: "^ethernet-phy@[0-9a-f]+$": type: object diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c index 2267bf75784e..832a24e2805c 100644 --- a/drivers/net/ethernet/freescale/fec_main.c +++ b/drivers/net/ethernet/freescale/fec_main.c @@ -2067,6 +2067,7 @@ static int fec_enet_mii_init(struct platform_device *pdev) struct device_node *node; int err = -ENXIO; u32 mii_speed, holdtime; + u32 bus_freq; /* * The i.MX28 dual fec interfaces are not equal. @@ -2094,15 +2095,20 @@ static int fec_enet_mii_init(struct platform_device *pdev) return -ENOENT; } + bus_freq = 2500000; /* 2.5MHz by default */ + node = of_get_child_by_name(pdev->dev.of_node, "mdio"); + if (node) + of_property_read_u32(node, "clock-frequency", &bus_freq); + /* - * Set MII speed to 2.5 MHz (= clk_get_rate() / 2 * phy_speed) + * Set MII speed (= clk_get_rate() / 2 * phy_speed) * * The formula for FEC MDC is 'ref_freq / (MII_SPEED x 2)' while * for ENET-MAC is 'ref_freq / ((MII_SPEED + 1) x 2)'. The i.MX28 * Reference Manual has an error on this, and gets fixed on i.MX6Q * document. */ - mii_speed = DIV_ROUND_UP(clk_get_rate(fep->clk_ipg), 5000000); + mii_speed = DIV_ROUND_UP(clk_get_rate(fep->clk_ipg), bus_freq * 2); if (fep->quirks & FEC_QUIRK_ENET_MAC) mii_speed--; if (mii_speed > 63) { @@ -2148,7 +2154,6 @@ static int fec_enet_mii_init(struct platform_device *pdev) fep->mii_bus->priv = fep; fep->mii_bus->parent = &pdev->dev; - node = of_get_child_by_name(pdev->dev.of_node, "mdio"); err = of_mdiobus_register(fep->mii_bus, node); of_node_put(node); if (err) From 3c01eb62d1bd85a5dd1d22d74339728666ae2c45 Mon Sep 17 00:00:00 2001 From: Andrew Lunn Date: Mon, 20 Apr 2020 00:04:02 +0200 Subject: [PATCH 3/3] net: ethernet: fec: Allow the MDIO preamble to be disabled An MDIO transaction normally starts with 32 1s as a preamble. However not all devices requires such a preamble. Add a device tree property which allows the preamble to be suppressed. This will half the size of the MDIO transaction, allowing faster transactions. But it should only be used when all devices on the bus support suppressed preamble. Suggested-by: Chris Healy Signed-off-by: Andrew Lunn Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller --- Documentation/devicetree/bindings/net/mdio.yaml | 6 ++++++ drivers/net/ethernet/freescale/fec_main.c | 9 ++++++++- 2 files changed, 14 insertions(+), 1 deletion(-) diff --git a/Documentation/devicetree/bindings/net/mdio.yaml b/Documentation/devicetree/bindings/net/mdio.yaml index ab4a9df8b8e2..cd6c6ae6dabb 100644 --- a/Documentation/devicetree/bindings/net/mdio.yaml +++ b/Documentation/devicetree/bindings/net/mdio.yaml @@ -45,6 +45,12 @@ properties: defined 2.5MHz should only be used when all devices on the bus support the given clock speed. + suppress-preamble: + description: + The 32 bit preamble should be suppressed. In order for this to + work, all devices on the bus must support suppressed preamble. + type: boolean + patternProperties: "^ethernet-phy@[0-9a-f]+$": type: object diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c index 832a24e2805c..1ae075a246a3 100644 --- a/drivers/net/ethernet/freescale/fec_main.c +++ b/drivers/net/ethernet/freescale/fec_main.c @@ -2064,6 +2064,7 @@ static int fec_enet_mii_init(struct platform_device *pdev) static struct mii_bus *fec0_mii_bus; struct net_device *ndev = platform_get_drvdata(pdev); struct fec_enet_private *fep = netdev_priv(ndev); + bool suppress_preamble = false; struct device_node *node; int err = -ENXIO; u32 mii_speed, holdtime; @@ -2097,8 +2098,11 @@ static int fec_enet_mii_init(struct platform_device *pdev) bus_freq = 2500000; /* 2.5MHz by default */ node = of_get_child_by_name(pdev->dev.of_node, "mdio"); - if (node) + if (node) { of_property_read_u32(node, "clock-frequency", &bus_freq); + suppress_preamble = of_property_read_bool(node, + "suppress-preamble"); + } /* * Set MII speed (= clk_get_rate() / 2 * phy_speed) @@ -2135,6 +2139,9 @@ static int fec_enet_mii_init(struct platform_device *pdev) fep->phy_speed = mii_speed << 1 | holdtime << 8; + if (suppress_preamble) + fep->phy_speed |= BIT(7); + writel(fep->phy_speed, fep->hwp + FEC_MII_SPEED); /* Clear any pending transaction complete indication */