git: f46d75c90f5f - main - ixgbe: improve MDIO performance by reducing semaphore/IPC delays

The branch main has been updated by adrian:

URL: https://cgit.FreeBSD.org/src/commit/?id=f46d75c90f5feb87259635134dde4da328282842

commit f46d75c90f5feb87259635134dde4da328282842
Author:     Adrian Chadd <adrian@FreeBSD.org>
AuthorDate: 2026-04-17 17:11:53 +0000
Commit:     Adrian Chadd <adrian@FreeBSD.org>
CommitDate: 2026-04-17 17:11:53 +0000

    ixgbe: improve MDIO performance by reducing semaphore/IPC delays
    
    Each MDIO transfer takes 8ms, and all of that is spent in a set
    of DELAY() calls, which is consuming a LOT of CPU.
    
    * Change the timeout in ixgbe_hic_unlocked() - doing IPC to the
      on-chip firmware - to a 1uS delay and bump timeout appropriately.
      This seems to finish in a couple of microseconds on my local
      test devices.
    
    * Change the 2ms sleep in ixgbe_release_swfw_sync_X540() to 2ms
      for EEPROM/flash, and 10uS otherwise.  10uS seems to work fine
      on my local testing, but the config EEPROM doesn't read right
      without this extra delay.
    
    The first change shouldn't change the driver behaviour, but the
    latter change is more intrusive and needs some wider testing.
    (My guess here is that there SHOULD have been some completion
    check somewhere in the EEPROM/flash IO path, and these sleeps
    are masking them.)
    
    Locally tested:
    
    * C3558 (Denverton) w/ X553 backplane
    
    Reviewed by:    kbowling
    Differential Revision:  https://reviews.freebsd.org/D50295
---
 sys/dev/ixgbe/ixgbe_common.c |  4 ++--
 sys/dev/ixgbe/ixgbe_x540.c   | 16 +++++++++++++++-
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/sys/dev/ixgbe/ixgbe_common.c b/sys/dev/ixgbe/ixgbe_common.c
index bff022585a03..9e827d2e5473 100644
--- a/sys/dev/ixgbe/ixgbe_common.c
+++ b/sys/dev/ixgbe/ixgbe_common.c
@@ -4631,11 +4631,11 @@ s32 ixgbe_hic_unlocked(struct ixgbe_hw *hw, u32 *buffer, u32 length,
 	/* Setting this bit tells the ARC that a new command is pending. */
 	IXGBE_WRITE_REG(hw, IXGBE_HICR, hicr | IXGBE_HICR_C);
 
-	for (i = 0; i < timeout; i++) {
+	for (i = 0; i < timeout * 1000; i++) {
 		hicr = IXGBE_READ_REG(hw, IXGBE_HICR);
 		if (!(hicr & IXGBE_HICR_C))
 			break;
-		msec_delay(1);
+		usec_delay(1);
 	}
 
 	/* For each command except "Apply Update" perform
diff --git a/sys/dev/ixgbe/ixgbe_x540.c b/sys/dev/ixgbe/ixgbe_x540.c
index 57cec5b52e18..561fe6f0f78a 100644
--- a/sys/dev/ixgbe/ixgbe_x540.c
+++ b/sys/dev/ixgbe/ixgbe_x540.c
@@ -878,7 +878,21 @@ void ixgbe_release_swfw_sync_X540(struct ixgbe_hw *hw, u32 mask)
 	IXGBE_WRITE_REG(hw, IXGBE_SWFW_SYNC_BY_MAC(hw), swfw_sync);
 
 	ixgbe_release_swfw_sync_semaphore(hw);
-	msec_delay(2);
+
+	/*
+	 * EEPROM / flash access requires a 2ms sleep or interacting with
+	 * them isn't stable.  However, a 2ms delay for all sync operations
+	 * is very expensive for MDIO access.
+	 *
+	 * So use a 10us delay for PHY0/PHY1 MDIO and management access and
+	 * 2ms for everything else.  This keep MDIO access (eg from a switch
+	 * driver) fast.
+	 */
+	if (mask &
+	    (IXGBE_GSSR_PHY0_SM | IXGBE_GSSR_PHY1_SM | IXGBE_GSSR_SW_MNG_SM))
+		usec_delay(10);
+	else
+		usec_delay(2000);
 }
 
 /**