Re: [PATCH net-next] net: wwan: mhi_wwan_mbim: Silence sequence number glitch errors

[Manivannan Sadhasivam]

On Wed, Feb 12, 2025 at 12:15:35PM +0100, Stephan Gerhold wrote:
> 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@xxxxxxxxxx>

Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>

- Mani

> ---
>  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 d5a9360323d29df4b6665bef0949e017c90876a4..8755c5e6a65b302c9ba2fe463e9eac58d956eaff 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);
> 
> ---
> base-commit: 4e41231249f4083a095085ff86e317e29313c2c3
> change-id: 20250206-mhi-wwan-mbim-sequence-glitch-cdbd2db5b3bb
> 
> Best regards,
> -- 
> Stephan Gerhold <stephan.gerhold@xxxxxxxxxx>
> 

-- 
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