linux-kernel - [iwl-net PATCH] idpf: reduce mbx

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Message-ID: <20251110205837.3140385-1-brianvv@google.com>
Date: Mon, 10 Nov 2025 20:58:37 +0000
From: Brian Vazquez <brianvv@...gle.com>
To: Brian Vazquez <brianvv.kernel@...il.com>, Tony Nguyen <anthony.l.nguyen@...el.com>, 
	Przemek Kitszel <przemyslaw.kitszel@...el.com>, "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
	intel-wired-lan@...ts.osuosl.org
Cc: David Decotigny <decot@...gle.com>, Anjali Singhai <anjali.singhai@...el.com>, 
	Sridhar Samudrala <sridhar.samudrala@...el.com>, linux-kernel@...r.kernel.org, 
	netdev@...r.kernel.org, emil.s.tantilov@...el.com, 
	Brian Vazquez <brianvv@...gle.com>
Subject: [iwl-net PATCH] idpf: reduce mbx_task schedule delay to 300us

During the IDPF init phase, the mailbox runs in poll mode until it is
configured to properly handle interrupts. The previous delay of 300ms is
excessively long for the mailbox polling mechanism, which causes a slow
initialization of ~2s:

echo 0000:06:12.4 > /sys/bus/pci/drivers/idpf/bind

[   52.444239] idpf 0000:06:12.4: enabling device (0000 -> 0002)
[   52.485005] idpf 0000:06:12.4: Device HW Reset initiated
[   54.177181] idpf 0000:06:12.4: PTP init failed, err=-EOPNOTSUPP
[   54.206177] idpf 0000:06:12.4: Minimum RX descriptor support not provided, using the default
[   54.206182] idpf 0000:06:12.4: Minimum TX descriptor support not provided, using the default

Changing the delay to 300us avoids the delays during the initial mailbox
transactions, making the init phase much faster:

[   83.342590] idpf 0000:06:12.4: enabling device (0000 -> 0002)
[   83.384402] idpf 0000:06:12.4: Device HW Reset initiated
[   83.518323] idpf 0000:06:12.4: PTP init failed, err=-EOPNOTSUPP
[   83.547430] idpf 0000:06:12.4: Minimum RX descriptor support not provided, using the default
[   83.547435] idpf 0000:06:12.4: Minimum TX descriptor support not provided, using the default

Signed-off-by: Brian Vazquez <brianvv@...gle.com>
---
 drivers/net/ethernet/intel/idpf/idpf_lib.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/idpf/idpf_lib.c b/drivers/net/ethernet/intel/idpf/idpf_lib.c
index 52fe45b42095..44fbffab9737 100644
--- a/drivers/net/ethernet/intel/idpf/idpf_lib.c
+++ b/drivers/net/ethernet/intel/idpf/idpf_lib.c
@@ -1313,7 +1313,7 @@ void idpf_mbx_task(struct work_struct *work)
 		idpf_mb_irq_enable(adapter);
 	else
 		queue_delayed_work(adapter->mbx_wq, &adapter->mbx_task,
-				   msecs_to_jiffies(300));
+				   usecs_to_jiffies(300));
 
 	idpf_recv_mb_msg(adapter, adapter->hw.arq);
 }
-- 
2.51.2.1041.gc1ab5b90ca-goog