[PATCH AUTOSEL 6.6 11/20] net: wwan: mhi_wwan_mbim: Silence sequence number glitch errors

Sasha Levin
2025-02-24T11:19:46Z

From: Stephan Gerhold <stephan.gerhold@linaro.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@linaro.org>
Reviewed-by: Loic Poulain <loic.poulain@linaro.org>
Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://patch.msgid.link/20250212-mhi-wwan-mbim-sequence-glitch-v1-1-503735977cbd@linaro.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.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 3f72ae943b294..b1b2870a054ba 100644
--- a/drivers/net/wwan/mhi_wwan_mbim.c
+++ b/drivers/net/wwan/mhi_wwan_mbim.c
@@ -209,7 +209,7 @@ 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