diff options
| -rw-r--r-- | drivers/net/usb/lan78xx.c | 105 |
1 files changed, 87 insertions, 18 deletions
diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c index bff53324c70a..58e3589e3b89 100644 --- a/drivers/net/usb/lan78xx.c +++ b/drivers/net/usb/lan78xx.c @@ -1554,10 +1554,12 @@ static void lan78xx_set_multicast(struct net_device *netdev) schedule_work(&pdata->set_multicast); } +static int lan78xx_configure_flowcontrol(struct lan78xx_net *dev, + bool tx_pause, bool rx_pause); + static int lan78xx_update_flowcontrol(struct lan78xx_net *dev, u8 duplex, u16 lcladv, u16 rmtadv) { - u32 flow = 0, fct_flow = 0; u8 cap; if (dev->fc_autoneg) @@ -1565,27 +1567,13 @@ static int lan78xx_update_flowcontrol(struct lan78xx_net *dev, u8 duplex, else cap = dev->fc_request_control; - if (cap & FLOW_CTRL_TX) - flow |= (FLOW_CR_TX_FCEN_ | 0xFFFF); - - if (cap & FLOW_CTRL_RX) - flow |= FLOW_CR_RX_FCEN_; - - if (dev->udev->speed == USB_SPEED_SUPER) - fct_flow = FLOW_CTRL_THRESHOLD(FLOW_ON_SS, FLOW_OFF_SS); - else if (dev->udev->speed == USB_SPEED_HIGH) - fct_flow = FLOW_CTRL_THRESHOLD(FLOW_ON_HS, FLOW_OFF_HS); - netif_dbg(dev, link, dev->net, "rx pause %s, tx pause %s", (cap & FLOW_CTRL_RX ? "enabled" : "disabled"), (cap & FLOW_CTRL_TX ? "enabled" : "disabled")); - lan78xx_write_reg(dev, FCT_FLOW, fct_flow); - - /* threshold value should be set before enabling flow */ - lan78xx_write_reg(dev, FLOW, flow); - - return 0; + return lan78xx_configure_flowcontrol(dev, + cap & FLOW_CTRL_TX, + cap & FLOW_CTRL_RX); } static void lan78xx_rx_urb_submit_all(struct lan78xx_net *dev); @@ -2551,6 +2539,87 @@ static int lan78xx_configure_usb(struct lan78xx_net *dev, int speed) } /** + * lan78xx_configure_flowcontrol - Set MAC and FIFO flow control configuration + * @dev: pointer to the LAN78xx device structure + * @tx_pause: enable transmission of pause frames + * @rx_pause: enable reception of pause frames + * + * This function configures the LAN78xx flow control settings by writing + * to the FLOW and FCT_FLOW registers. The pause time is set to the + * maximum allowed value (65535 quanta). FIFO thresholds are selected + * based on USB speed. + * + * The Pause Time field is measured in units of 512-bit times (quanta): + * - At 1 Gbps: 1 quanta = 512 ns → max ~33.6 ms pause + * - At 100 Mbps: 1 quanta = 5.12 µs → max ~335 ms pause + * - At 10 Mbps: 1 quanta = 51.2 µs → max ~3.3 s pause + * + * Flow control thresholds (FCT_FLOW) are used to trigger pause/resume: + * - RXUSED is the number of bytes used in the RX FIFO + * - Flow is turned ON when RXUSED ≥ FLOW_ON threshold + * - Flow is turned OFF when RXUSED ≤ FLOW_OFF threshold + * - Both thresholds are encoded in units of 512 bytes (rounded up) + * + * Thresholds differ by USB speed because available USB bandwidth + * affects how fast packets can be drained from the RX FIFO: + * - USB 3.x (SuperSpeed): + * FLOW_ON = 9216 bytes → 18 units + * FLOW_OFF = 4096 bytes → 8 units + * - USB 2.0 (High-Speed): + * FLOW_ON = 8704 bytes → 17 units + * FLOW_OFF = 1024 bytes → 2 units + * + * Note: The FCT_FLOW register must be configured before enabling TX pause + * (i.e., before setting FLOW_CR_TX_FCEN_), as required by the hardware. + * + * Return: 0 on success or a negative error code on failure. + */ +static int lan78xx_configure_flowcontrol(struct lan78xx_net *dev, + bool tx_pause, bool rx_pause) +{ + /* Use maximum pause time: 65535 quanta (512-bit times) */ + const u32 pause_time_quanta = 65535; + u32 fct_flow = 0; + u32 flow = 0; + int ret; + + /* Prepare MAC flow control bits */ + if (tx_pause) + flow |= FLOW_CR_TX_FCEN_ | pause_time_quanta; + + if (rx_pause) + flow |= FLOW_CR_RX_FCEN_; + + /* Select RX FIFO thresholds based on USB speed + * + * FCT_FLOW layout: + * bits [6:0] FLOW_ON threshold (RXUSED ≥ ON → assert pause) + * bits [14:8] FLOW_OFF threshold (RXUSED ≤ OFF → deassert pause) + * thresholds are expressed in units of 512 bytes + */ + switch (dev->udev->speed) { + case USB_SPEED_SUPER: + fct_flow = FLOW_CTRL_THRESHOLD(FLOW_ON_SS, FLOW_OFF_SS); + break; + case USB_SPEED_HIGH: + fct_flow = FLOW_CTRL_THRESHOLD(FLOW_ON_HS, FLOW_OFF_HS); + break; + default: + netdev_warn(dev->net, "Unsupported USB speed: %d\n", + dev->udev->speed); + return -EINVAL; + } + + /* Step 1: Write FIFO thresholds before enabling pause frames */ + ret = lan78xx_write_reg(dev, FCT_FLOW, fct_flow); + if (ret < 0) + return ret; + + /* Step 2: Enable MAC pause functionality */ + return lan78xx_write_reg(dev, FLOW, flow); +} + +/** * lan78xx_register_fixed_phy() - Register a fallback fixed PHY * @dev: LAN78xx device * |