// SPDX-License-Identifier: GPL-2.0+ #include <linux/linkmode.h> /** * linkmode_resolve_pause - resolve the allowable pause modes * @local_adv: local advertisement in ethtool format * @partner_adv: partner advertisement in ethtool format * @tx_pause: pointer to bool to indicate whether transmit pause should be * enabled. * @rx_pause: pointer to bool to indicate whether receive pause should be * enabled. * * Flow control is resolved according to our and the link partners * advertisements using the following drawn from the 802.3 specs: * Local device Link partner * Pause AsymDir Pause AsymDir Result * 0 X 0 X Disabled * 0 1 1 0 Disabled * 0 1 1 1 TX * 1 0 0 X Disabled * 1 X 1 X TX+RX * 1 1 0 1 RX */ void linkmode_resolve_pause(const unsigned long *local_adv, const unsigned long *partner_adv, bool *tx_pause, bool *rx_pause) { … } EXPORT_SYMBOL_GPL(…); /** * linkmode_set_pause - set the pause mode advertisement * @advertisement: advertisement in ethtool format * @tx: boolean from ethtool struct ethtool_pauseparam tx_pause member * @rx: boolean from ethtool struct ethtool_pauseparam rx_pause member * * Configure the advertised Pause and Asym_Pause bits according to the * capabilities of provided in @tx and @rx. * * We convert as follows: * tx rx Pause AsymDir * 0 0 0 0 * 0 1 1 1 * 1 0 0 1 * 1 1 1 0 * * Note: this translation from ethtool tx/rx notation to the advertisement * is actually very problematical. Here are some examples: * * For tx=0 rx=1, meaning transmit is unsupported, receive is supported: * * Local device Link partner * Pause AsymDir Pause AsymDir Result * 1 1 1 0 TX + RX - but we have no TX support. * 1 1 0 1 Only this gives RX only * * For tx=1 rx=1, meaning we have the capability to transmit and receive * pause frames: * * Local device Link partner * Pause AsymDir Pause AsymDir Result * 1 0 0 1 Disabled - but since we do support tx and rx, * this should resolve to RX only. * * Hence, asking for: * rx=1 tx=0 gives Pause+AsymDir advertisement, but we may end up * resolving to tx+rx pause or only rx pause depending on * the partners advertisement. * rx=0 tx=1 gives AsymDir only, which will only give tx pause if * the partners advertisement allows it. * rx=1 tx=1 gives Pause only, which will only allow tx+rx pause * if the other end also advertises Pause. */ void linkmode_set_pause(unsigned long *advertisement, bool tx, bool rx) { … } EXPORT_SYMBOL_GPL(…);
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