linux-kernel - [PATCH AUTOSEL 6.13 21/32] net: wwan: mhi_wwan_mbim: Silence sequence number glitch errors

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Message-Id: <20250224111638.2212832-21-sashal@kernel.org>
Date: Mon, 24 Feb 2025 06:16:27 -0500
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Stephan Gerhold <stephan.gerhold@...aro.org>,
	Loic Poulain <loic.poulain@...aro.org>,
	Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
	Jakub Kicinski <kuba@...nel.org>,
	Sasha Levin <sashal@...nel.org>,
	ryazanov.s.a@...il.com,
	andrew+netdev@...n.ch,
	davem@...emloft.net,
	edumazet@...gle.com,
	pabeni@...hat.com,
	netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 6.13 21/32] net: wwan: mhi_wwan_mbim: Silence sequence number glitch errors

From: Stephan Gerhold <stephan.gerhold@...aro.org>

[ Upstream commit 0d1fac6d26aff5df21bb4ec980d9b7a11c410b96 ]

When using the Qualcomm X55 modem on the ThinkPad X13s, the kernel log is
constantly being filled with errors related to a "sequence number glitch",
e.g.:

	[ 1903.284538] sequence number glitch prev=16 curr=0
	[ 1913.812205] sequence number glitch prev=50 curr=0
	[ 1923.698219] sequence number glitch prev=142 curr=0
	[ 2029.248276] sequence number glitch prev=1555 curr=0
	[ 2046.333059] sequence number glitch prev=70 curr=0
	[ 2076.520067] sequence number glitch prev=272 curr=0
	[ 2158.704202] sequence number glitch prev=2655 curr=0
	[ 2218.530776] sequence number glitch prev=2349 curr=0
	[ 2225.579092] sequence number glitch prev=6 curr=0

Internet connectivity is working fine, so this error seems harmless. It
looks like modem does not preserve the sequence number when entering low
power state; the amount of errors depends on how actively the modem is
being used.

A similar issue has also been seen on USB-based MBIM modems [1]. However,
in cdc_ncm.c the "sequence number glitch" message is a debug message
instead of an error. Apply the same to the mhi_wwan_mbim.c driver to
silence these errors when using the modem.

[1]: https://lists.freedesktop.org/archives/libmbim-devel/2016-November/000781.html

Signed-off-by: Stephan Gerhold <stephan.gerhold@...aro.org>
Reviewed-by: Loic Poulain <loic.poulain@...aro.org>
Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Link: https://patch.msgid.link/20250212-mhi-wwan-mbim-sequence-glitch-v1-1-503735977cbd@linaro.org
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/net/wwan/mhi_wwan_mbim.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wwan/mhi_wwan_mbim.c b/drivers/net/wwan/mhi_wwan_mbim.c
index d5a9360323d29..8755c5e6a65b3 100644
--- a/drivers/net/wwan/mhi_wwan_mbim.c
+++ b/drivers/net/wwan/mhi_wwan_mbim.c
@@ -220,7 +220,7 @@ static int mbim_rx_verify_nth16(struct mhi_mbim_context *mbim, struct sk_buff *s
 	if (mbim->rx_seq + 1 != le16_to_cpu(nth16->wSequence) &&
 	    (mbim->rx_seq || le16_to_cpu(nth16->wSequence)) &&
 	    !(mbim->rx_seq == 0xffff && !le16_to_cpu(nth16->wSequence))) {
-		net_err_ratelimited("sequence number glitch prev=%d curr=%d\n",
+		net_dbg_ratelimited("sequence number glitch prev=%d curr=%d\n",
 				    mbim->rx_seq, le16_to_cpu(nth16->wSequence));
 	}
 	mbim->rx_seq = le16_to_cpu(nth16->wSequence);
-- 
2.39.5