[PATCH v9 6/9] wifi: ath12k: add support for setting fixed HE rate/GI/LTF

[Pradeep Kumar Chitrapu]

On 1/24/2025 12:26 AM, Maxime Bizon wrote:
> 
> On Thu, 2025-01-23 at 17:09 -0800, Pradeep Kumar Chitrapu wrote:
> 
> Hello,
> 
>> I believe, this is default GI based on device capability of HE for
>> ath11k or EHT for ath12k.
> 
> Your patch alters the behaviour of this code in
> ath12k_peer_assoc_h_ht():
> 
>          /* As firmware handles these two flags (IEEE80211_HT_CAP_SGI_20
>           * and IEEE80211_HT_CAP_SGI_40) for enabling SGI, reset both
>           * flags if guard interval is Default GI
>           */
> 	if (arvif->bitrate_mask.control[band].gi == NL80211_TXRATE_DEFAULT_GI)
> 	        arg->peer_ht_caps &= ~(IEEE80211_HT_CAP_SGI_20 |
> 				IEEE80211_HT_CAP_SGI_40);
> 
> 	if (arvif->bitrate_mask.control[band].gi != NL80211_TXRATE_FORCE_LGI) {
> 		if (ht_cap->cap & (IEEE80211_HT_CAP_SGI_20 |
> 	            IEEE80211_HT_CAP_SGI_40))
>                          arg->peer_rate_caps |= WMI_HOST_RC_SGI_FLAG;
> 	}
> 
> 
> I don't understand why a patch adding a feature to force GI would alter
> the current behaviour without any actual forcing ?
> 
Hi Maxime,

Apologize for my earlier comment. Firmware relies on peer_rate_caps and 
bandwidth settings when configuring GI. Currently default is configured 
as FORCE_SGI. When there is fixed rate settings configured from user 
space to override defaults to replace SHORT GI with DEFAULT_GI, the code 
snippet you mentioned ensures honoring this by removing HT_CAP_SGI_20 
and HT_CAP_SGI_40. The behavior has been same for ath11k driver as well.

I will get back with more detailed information as soon as possible.

Thanks for understanding,

Best regards,
Pradeep