Date: Mon, 03 Aug 2026 10:38:05 +0000 From: Kevin Bowling <kbowling@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 709426551c6a - main - igc: Work around I225 v1 minimum IPG erratum Message-ID: <6a706f8d.4471d.5271f968@gitrepo.freebsd.org>
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The branch main has been updated by kbowling: URL: https://cgit.FreeBSD.org/src/commit/?id=709426551c6a3607fb5a33f5b8dbb87cfa9c8125 commit 709426551c6a3607fb5a33f5b8dbb87cfa9c8125 Author: Kevin Bowling <kbowling@FreeBSD.org> AuthorDate: 2026-08-03 10:28:49 +0000 Commit: Kevin Bowling <kbowling@FreeBSD.org> CommitDate: 2026-08-03 10:37:09 +0000 igc: Work around I225 v1 minimum IPG erratum I225 v1 cannot receive the minimum inter-packet gap required at 2.5 Gb/s. For affected back-to-back links, Intel recommends using a 15-byte transmit IPG instead of 12 bytes. Program TIPG.IPGT to 0xb for pre-v2 I225 devices at 2.5 Gb/s and restore the default at lower speeds. Avoid penalizing fixed I225 and I226 parts. MFC after: 2 weeks --- sys/dev/igc/if_igc.c | 29 +++++++++++++++++++++++++++++ sys/dev/igc/igc_defines.h | 1 + 2 files changed, 30 insertions(+) diff --git a/sys/dev/igc/if_igc.c b/sys/dev/igc/if_igc.c index 4a54d8ca7a6c..fa4f427a5710 100644 --- a/sys/dev/igc/if_igc.c +++ b/sys/dev/igc/if_igc.c @@ -128,6 +128,7 @@ static int igc_if_rx_queue_intr_enable(if_ctx_t, uint16_t); static int igc_if_tx_queue_intr_enable(if_ctx_t, uint16_t); static void igc_if_multi_set(if_ctx_t); static void igc_if_update_admin_status(if_ctx_t); +static void igc_apply_i225_ipg_workaround(struct igc_softc *); static void igc_if_debug(if_ctx_t); static void igc_update_stats_counters(struct igc_softc *); static void igc_add_hw_stats(struct igc_softc *); @@ -1400,6 +1401,33 @@ igc_if_timer(if_ctx_t ctx, uint16_t qid) iflib_admin_intr_deferred(ctx); } +static void +igc_apply_i225_ipg_workaround(struct igc_softc *sc) +{ + struct igc_hw *hw = &sc->hw; + u32 ipgt, tipg; + + /* + * I225 v1 cannot receive the minimum IPG required at 2.5 Gb/s. + * Intel's documented back-to-back workaround is for the transmitter + * to use a 15-byte IPG instead of 12 bytes. I225 v2 and later have + * the receive-side fix and should retain the standard IPG. + */ + if (!igc_is_device_id_i225(hw) || + hw->revision_id >= IGC_REVISION_2) + return; + + ipgt = sc->link_speed == SPEED_2500 ? IGC_I225_TIPG_IPGT_2P5 : + DEFAULT_82543_TIPG_IPGT_COPPER; + tipg = IGC_READ_REG(hw, IGC_TIPG); + if ((tipg & IGC_TIPG_IPGT_MASK) == ipgt) + return; + + tipg &= ~IGC_TIPG_IPGT_MASK; + tipg |= ipgt; + IGC_WRITE_REG(hw, IGC_TIPG, tipg); +} + static void igc_if_update_admin_status(if_ctx_t ctx) { @@ -1445,6 +1473,7 @@ igc_if_update_admin_status(if_ctx_t ctx) sc->link_active = 0; iflib_link_state_change(ctx, LINK_STATE_DOWN, 0); } + igc_apply_i225_ipg_workaround(sc); igc_update_stats_counters(sc); } diff --git a/sys/dev/igc/igc_defines.h b/sys/dev/igc/igc_defines.h index 09f75fe2787e..3e6309176204 100644 --- a/sys/dev/igc/igc_defines.h +++ b/sys/dev/igc/igc_defines.h @@ -364,6 +364,7 @@ /* Default values for the transmit IPG register */ #define DEFAULT_82543_TIPG_IPGT_FIBER 9 #define DEFAULT_82543_TIPG_IPGT_COPPER 8 +#define IGC_I225_TIPG_IPGT_2P5 0xB #define IGC_TIPG_IPGT_MASK 0x000003FFhome | help
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