Re: [PATCH 02/10] carl9170: mac80211: advertise RX STBC capability

[Christian Lamparter <chunkeey@gmail.com>]

On 3/12/26 11:37 AM, Masi Osmani wrote:
> The AR9170 baseband supports receiving Space-Time Block Coded
> streams (1 spatial stream).  The capability was not advertised
> in the HT capabilities, causing peers to never use STBC when
> transmitting to us.  Enabling RX STBC improves receive diversity
> gain and link reliability, especially in multipath environments.
> 
> The ath9k driver for the same chipset family advertises RX STBC
> based on the number of RX chains.  With 2 RX chains, the AR9170
> can decode 1 STBC spatial stream.


No, not that I can tell.

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/net/wireless/ath/ath9k/common-init.c?h=v7.0-rc4#n204

|        if (AR_SREV_9280_20_OR_LATER(ah)) {
|                if (max_streams >= 2)
|                        ht_info->cap |= IEEE80211_HT_CAP_TX_STBC;
|                ht_info->cap |= (1 << IEEE80211_HT_CAP_RX_STBC_SHIFT);
|        }

the ath9k driver supports this for generation after the AR9160, the AR9280

The commit message is wrong again. If you are sure this is working though,
please rewrite the commit message and put this feature after a experimental
module parameter (like for the STBC patch you proposed).

Cheers,
Christian


> Signed-off-by: Masi Osmani <mas-i@hotmail.de>
> ---
>   drivers/net/wireless/ath/carl9170/main.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/ath/carl9170/main.c b/drivers/net/wireless/ath/carl9170/main.c
> index aa7e481..6324b38 100644
> --- a/drivers/net/wireless/ath/carl9170/main.c
> +++ b/drivers/net/wireless/ath/carl9170/main.c
> @@ -156,7 +156,8 @@ static struct ieee80211_channel carl9170_5ghz_chantable[] = {
>   			  IEEE80211_HT_CAP_SGI_40 |			\
>   			  IEEE80211_HT_CAP_SGI_20 |			\
>   			  IEEE80211_HT_CAP_DSSSCCK40 |			\
> -			  IEEE80211_HT_CAP_SM_PS,			\
> +			  IEEE80211_HT_CAP_SM_PS |			\
> +			  (1 << IEEE80211_HT_CAP_RX_STBC_SHIFT),	\
>   	.ampdu_factor	= IEEE80211_HT_MAX_AMPDU_64K,			\
>   	.ampdu_density	= IEEE80211_HT_MPDU_DENSITY_8,			\
>   	.mcs		= {						\