/* * TCP HYBLA * * TCP-HYBLA Congestion control algorithm, based on: * C.Caini, R.Firrincieli, "TCP-Hybla: A TCP Enhancement * for Heterogeneous Networks", * International Journal on satellite Communications, * September 2004 * Daniele Lacamera * root at danielinux.net */ #include #include /* Tcp Hybla structure. */ struct hybla { bool hybla_en; u32 snd_cwnd_cents; /* Keeps increment values when it is <1, <<7 */ u32 rho; /* Rho parameter, integer part */ u32 rho2; /* Rho * Rho, integer part */ u32 rho_3ls; /* Rho parameter, <<3 */ u32 rho2_7ls; /* Rho^2, <<7 */ u32 minrtt_us; /* Minimum smoothed round trip time value seen */ }; /* Hybla reference round trip time (default= 1/40 sec = 25 ms), in ms */ static int rtt0 = 25; module_param(rtt0, int, 0644); MODULE_PARM_DESC(rtt0, "reference rout trip time (ms)"); /* This is called to refresh values for hybla parameters */ static inline void hybla_recalc_param (struct sock *sk) { struct hybla *ca = inet_csk_ca(sk); ca->rho_3ls = max_t(u32, tcp_sk(sk)->srtt_us / (rtt0 * USEC_PER_MSEC), 8U); ca->rho = ca->rho_3ls >> 3; ca->rho2_7ls = (ca->rho_3ls * ca->rho_3ls) << 1; ca->rho2 = ca->rho2_7ls >> 7; } static void hybla_init(struct sock *sk) { struct tcp_sock *tp = tcp_sk(sk); struct hybla *ca = inet_csk_ca(sk); ca->rho = 0; ca->rho2 = 0; ca->rho_3ls = 0; ca->rho2_7ls = 0; ca->snd_cwnd_cents = 0; ca->hybla_en = true; tp->snd_cwnd = 2; tp->snd_cwnd_clamp = 65535; /* 1st Rho measurement based on initial srtt */ hybla_recalc_param(sk); /* set minimum rtt as this is the 1st ever seen */ ca->minrtt_us = tp->srtt_us; tp->snd_cwnd = ca->rho; } static void hybla_state(struct sock *sk, u8 ca_state) { struct hybla *ca = inet_csk_ca(sk); ca->hybla_en = (ca_state == TCP_CA_Open); } static inline u32 hybla_fraction(u32 odds) { static const u32 fractions[] = { 128, 139, 152, 165, 181, 197, 215, 234, }; return (odds < ARRAY_SIZE(fractions)) ? fractions[odds] : 128; } /* TCP Hybla main routine. * This is the algorithm behavior: * o Recalc Hybla parameters if min_rtt has changed * o Give cwnd a new value based on the model proposed * o remember increments <1 */ static void hybla_cong_avoid(struct sock *sk, u32 ack, u32 acked) { struct tcp_sock *tp = tcp_sk(sk); struct hybla *ca = inet_csk_ca(sk); u32 increment, odd, rho_fractions; int is_slowstart = 0; /* Recalculate rho only if this srtt is the lowest */ if (tp->srtt_us < ca->minrtt_us) { hybla_recalc_param(sk); ca->minrtt_us = tp->srtt_us; } if (!tcp_is_cwnd_limited(sk)) return; if (!ca->hybla_en) { tcp_reno_cong_avoid(sk, ack, acked); return; } if (ca->rho == 0) hybla_recalc_param(sk); rho_fractions = ca->rho_3ls - (ca->rho << 3); if (tcp_in_slow_start(tp)) { /* * slow start * INC = 2^RHO - 1 * This is done by splitting the rho parameter * into 2 parts: an integer part and a fraction part. * Inrement<<7 is estimated by doing: * [2^(int+fract)]<<7 * that is equal to: * (2^int) * [(2^fract) <<7] * 2^int is straightly computed as 1<rho, 16U)) * hybla_fraction(rho_fractions)) - 128; } else { /* * congestion avoidance * INC = RHO^2 / W * as long as increment is estimated as (rho<<7)/window * it already is <<7 and we can easily count its fractions. */ increment = ca->rho2_7ls / tp->snd_cwnd; if (increment < 128) tp->snd_cwnd_cnt++; } odd = increment % 128; tp->snd_cwnd += increment >> 7; ca->snd_cwnd_cents += odd; /* check when fractions goes >=128 and increase cwnd by 1. */ while (ca->snd_cwnd_cents >= 128) { tp->snd_cwnd++; ca->snd_cwnd_cents -= 128; tp->snd_cwnd_cnt = 0; } /* check when cwnd has not been incremented for a while */ if (increment == 0 && odd == 0 && tp->snd_cwnd_cnt >= tp->snd_cwnd) { tp->snd_cwnd++; tp->snd_cwnd_cnt = 0; } /* clamp down slowstart cwnd to ssthresh value. */ if (is_slowstart) tp->snd_cwnd = min(tp->snd_cwnd, tp->snd_ssthresh); tp->snd_cwnd = min_t(u32, tp->snd_cwnd, tp->snd_cwnd_clamp); } static struct tcp_congestion_ops tcp_hybla __read_mostly = { .init = hybla_init, .ssthresh = tcp_reno_ssthresh, .undo_cwnd = tcp_reno_undo_cwnd, .cong_avoid = hybla_cong_avoid, .set_state = hybla_state, .owner = THIS_MODULE, .name = "hybla" }; static int __init hybla_register(void) { BUILD_BUG_ON(sizeof(struct hybla) > ICSK_CA_PRIV_SIZE); return tcp_register_congestion_control(&tcp_hybla); } static void __exit hybla_unregister(void) { tcp_unregister_congestion_control(&tcp_hybla); } module_init(hybla_register); module_exit(hybla_unregister); MODULE_AUTHOR("Daniele Lacamera"); MODULE_LICENSE("GPL"); MODULE_DESCRIPTION("TCP Hybla"); td>Geert Uytterhoeven <geert@linux-m68k.org>2016-12-18 10:19:28 +0100 committerJohan Hovold <johan@kernel.org>2017-01-02 10:31:08 +0100 commit427157631648c980e8bba4d73a21508b9e1a47ec (patch) tree7a72996439dd2c52ba443262a4af93628ed151d9 /include/dt-bindings/i2c parent0c744ea4f77d72b3dcebb7a8f2684633ec79be88 (diff)
USB: serial: f81534: detect errors from f81534_logic_to_phy_port()
With gcc 4.1.2: drivers/usb/serial/f81534.c: In function ‘f81534_port_probe’: drivers/usb/serial/f81534.c:1250: warning: comparison is always false due to limited range of data type f81534_logic_to_phy_port() may return a negative error value, which is ignored by assigning it to u8 f81534_port_private.phy_num. Use an intermediate variable of type int to fix this. While at it, forward the actual error code instead of converting it to -ENODEV, and drop the useless check for F81534_NUM_PORT, as the callee always returns a valid port number in case of success. Fixes: 0c9bd6004d258d46 ("USB: serial: add Fintek F81532/534 driver") Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Johan Hovold <johan@kernel.org>
Diffstat (limited to 'include/dt-bindings/i2c')