[PATCH] wifi: iwlwifi: mld: include VI packets in low latency detection

[PATCH] wifi: iwlwifi: mld: include VI packets in low latency detection

[Endrik Einberg]

iwl_mld_is_vo_vi_pkt() checks whether the mapped access category
is less than IEEE80211_AC_VI.
Since mac80211 defines IEEE80211_AC_VO as 0 and IEEE80211_AC_VI as 1,
this only matches voice traffic and excludes video traffic.

Include IEEE80211_AC_VI as intended,
matching behaviour of iwlmvm's iwl_mvm_calc_tcm_stats().

Fixes: d1e879ec600f ("wifi: iwlwifi: add iwlmld sub-driver")
Signed-off-by: Endrik Einberg <git@endrik.dev>
---
 drivers/net/wireless/intel/iwlwifi/mld/low_latency.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/intel/iwlwifi/mld/low_latency.c b/drivers/net/wireless/intel/iwlwifi/mld/low_latency.c
index a4ddc32e2860..36da639aee54 100644
--- a/drivers/net/wireless/intel/iwlwifi/mld/low_latency.c
+++ b/drivers/net/wireless/intel/iwlwifi/mld/low_latency.c
@@ -257,7 +257,7 @@ static bool iwl_mld_is_vo_vi_pkt(struct ieee80211_hdr *hdr)
 	if (tid >= IWL_MAX_TID_COUNT)
 		return false;
 
-	return tid_to_mac80211_ac[tid] < IEEE80211_AC_VI;
+	return tid_to_mac80211_ac[tid] <= IEEE80211_AC_VI;
 }
 
 void iwl_mld_low_latency_update_counters(struct iwl_mld *mld,
-- 
2.53.0

Re: [PATCH] wifi: iwlwifi: mld: include VI packets in low latency detection

[netdev-bot+sinfo]

Hi!

This is an automated message. This series looks like a fix, but its
commit messages seem to be missing some information:

 - How the issue was discovered, e.g. hit in production, hit during
   development, syzbot report, manual code inspection, LLM or static
   analysis tool scan.

 - Whether the issue was actually triggered, or is only theoretical
   (e.g. found by code inspection). If it was triggered please include
   the symptoms, like the stack trace or error messages.

Please do not repost the series just to address the above. Instead,
reply to this email with the missing information, so that reviewers
can take it into account. If the series needs another revision for
other reasons, please include the information in the commit messages
then.

The evaluation is done by an LLM so it may be wrong, if you think
that is the case please reply and explain.

Re: [PATCH] wifi: iwlwifi: mld: include VI packets in low latency detection

[Endrik Einberg]

Hi,

This was discovered during Wi-Fi troubleshooting with LLM assistance,
then confirmed through runtime testing and manual code inspection.

Synthetic video-priority UDP traffic did not automatically
activate low-latency mode, whereas voice-priority traffic did
(observed through the iwlmld debugfs state).

This is definitely not a theoretical bug.
Whether it causes actual noticeable performance issues is unconfirmed.

Thanks,
Endrik

RE: [PATCH] wifi: iwlwifi: mld: include VI packets in low latency detection

[Korenblit, Miriam Rachel]

> -----Original Message-----
> From: Endrik Einberg <git@endrik.dev>
> Sent: Monday, October 5, 2026 12:45 AM
> To: Korenblit, Miriam Rachel <miriam.rachel.korenblit@intel.com>
> Cc: linux-wireless@vger.kernel.org; netdev@vger.kernel.org; linux-
> kernel@vger.kernel.org; Endrik Einberg <git@endrik.dev>
> Subject: [PATCH] wifi: iwlwifi: mld: include VI packets in low latency detection
> 
> iwl_mld_is_vo_vi_pkt() checks whether the mapped access category is less than
> IEEE80211_AC_VI.
> Since mac80211 defines IEEE80211_AC_VO as 0 and IEEE80211_AC_VI as 1, this
> only matches voice traffic and excludes video traffic.
> 
> Include IEEE80211_AC_VI as intended,
> matching behaviour of iwlmvm's iwl_mvm_calc_tcm_stats().
> 
> Fixes: d1e879ec600f ("wifi: iwlwifi: add iwlmld sub-driver")
> Signed-off-by: Endrik Einberg <git@endrik.dev>
> ---
>  drivers/net/wireless/intel/iwlwifi/mld/low_latency.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/intel/iwlwifi/mld/low_latency.c
> b/drivers/net/wireless/intel/iwlwifi/mld/low_latency.c
> index a4ddc32e2860..36da639aee54 100644
> --- a/drivers/net/wireless/intel/iwlwifi/mld/low_latency.c
> +++ b/drivers/net/wireless/intel/iwlwifi/mld/low_latency.c
> @@ -257,7 +257,7 @@ static bool iwl_mld_is_vo_vi_pkt(struct ieee80211_hdr
> *hdr)
>  	if (tid >= IWL_MAX_TID_COUNT)
>  		return false;
> 
> -	return tid_to_mac80211_ac[tid] < IEEE80211_AC_VI;
> +	return tid_to_mac80211_ac[tid] <= IEEE80211_AC_VI;

I don't want to rely on the value of the different enums too much.
Let's be explicit:
return tid_to_mac80211_ac[tid]  == IEEE80211_AC_VI ||
            tid_to_mac80211_ac[tid]  == IEEE80211_AC_VO
>  }
> 
>  void iwl_mld_low_latency_update_counters(struct iwl_mld *mld,
> --
> 2.53.0

Re: [PATCH] wifi: iwlwifi: mld: include VI packets in low latency detection

[git]

> I don't want to rely on the value of the different enums too much.
> Let's be explicit:
> return tid_to_mac80211_ac[tid]  == IEEE80211_AC_VI ||
>             tid_to_mac80211_ac[tid]  == IEEE80211_AC_VO

Hey,

I actually considered that initially, but as a kernel newbie,
I thought a minimal patch would result in less hassle for reviewers.

A v2 with the explicit comparison is coming shortly.

Thanks,
Endrik