From bc99862101aaf7b6496a29ab811e3f54d68702fb Mon Sep 17 00:00:00 2001
From: Ad Schellevis <ad@opnsense.org>
Date: Tue, 9 Nov 2021 17:21:43 +0100
Subject: [PATCH] ixgbe: workaround to prevent an i2c bus read to keep trying
 to read an empty slot

When executing `ifconfig -v` this will lead to stalls for a second per
interface due to the timeout being set to a static 10 without a module
placed, this patch makes sure this is only allowed once per insertion.
---
 sys/dev/ixgbe/if_ix.c      |  6 ++++++
 sys/dev/ixgbe/ixgbe_phy.c  | 12 ++++++++++++
 sys/dev/ixgbe/ixgbe_type.h |  2 ++
 3 files changed, 20 insertions(+)

diff --git a/sys/dev/ixgbe/if_ix.c b/sys/dev/ixgbe/if_ix.c
index 959afa79e7d..cea6d1752f2 100644
--- a/sys/dev/ixgbe/if_ix.c
+++ b/sys/dev/ixgbe/if_ix.c
@@ -1135,6 +1135,12 @@ ixgbe_if_attach_post(if_ctx_t ctx)
 	sc = iflib_get_softc(ctx);
 	hw = &sc->hw;
 
+	/**
+	 * XXX: Since we don't seem to be able to flag a missing module, make sure we don't keep reading an i2c bus for something that isn't there
+	 *      sfp_probe_timed_out will be set when i2c probe timeout is reached and will be reset on reinit using this event.
+	 */
+	hw->sfp_probe_timed_out = false;
+
 	if (sc->intr_type == IFLIB_INTR_LEGACY &&
 		(sc->feat_cap & IXGBE_FEATURE_LEGACY_IRQ) == 0) {
 		device_printf(dev, "Device does not support legacy interrupts");
diff --git a/sys/dev/ixgbe/ixgbe_phy.c b/sys/dev/ixgbe/ixgbe_phy.c
index 2a735ead9a1..4b85b43d4c6 100644
--- a/sys/dev/ixgbe/ixgbe_phy.c
+++ b/sys/dev/ixgbe/ixgbe_phy.c
@@ -2033,6 +2033,15 @@ static s32 ixgbe_read_i2c_byte_generic_int(struct ixgbe_hw *hw, u8 byte_offset,
 	if (ixgbe_is_sfp_probe(hw, byte_offset, dev_addr))
 		max_retry = IXGBE_SFP_DETECT_RETRIES;
 
+	/***
+	 * XXX : Workaround to prevent reading an sfp slot with nothing connected to it.
+	 *       There likely should be some signal to detect an empty slot, trying to keep reading for 1 second on every attempt isn't very practical
+	 *       sfp_probe_timed_out is reset on ixgbe_if_attach_post() which should be triggered on module placement.
+	 */
+	if (hw->sfp_probe_timed_out) {
+		max_retry = 0;
+	}
+
 	do {
 		if (lock && hw->mac.ops.acquire_swfw_sync(hw, swfw_mask))
 			return IXGBE_ERR_SWFW_SYNC;
@@ -2091,6 +2100,9 @@ fail:
 		retry++;
 	} while (retry <= max_retry);
 
+	/* XXX it's probably enough to set this to true since we are in the error path */
+	hw->sfp_probe_timed_out = hw->sfp_probe_timed_out || retry >= max_retry;
+
 	return status;
 }
 
diff --git a/sys/dev/ixgbe/ixgbe_type.h b/sys/dev/ixgbe/ixgbe_type.h
index 91b46da72c7..32d8085edef 100644
--- a/sys/dev/ixgbe/ixgbe_type.h
+++ b/sys/dev/ixgbe/ixgbe_type.h
@@ -4260,6 +4260,8 @@ struct ixgbe_hw {
 	bool allow_unsupported_sfp;
 	bool wol_enabled;
 	bool need_crosstalk_fix;
+	/* XXX flag for workaround to prevent reading an sfp[+] slot with nothing connected to it. */
+	bool sfp_probe_timed_out;
 	u32 fw_rst_cnt;
 };