Re: [PATCH wireless-next 4/8] wifi: rt2800: report the MCS16 to MCS8 fallback of RT3593 in TX status

[Stanislaw Gruszka <stf_xl@wp.pl>]

On Thu, Oct 29, 2026 at 09:47:45PM +0800, Ho Jie Feng wrote:
> The RT3593 retry chain is now MCS 16 to MCS 8, skipping 7 MCS
> rates in between. Reflect that in the retry calculation code.
> 
> Test results:
>    before after
> TX 27.0   29.4
> RX 70.0   70.0

I think this patch should be merged with patch 3, and also 
similar handling should be done for RT3883 since it has
the same fallback pattern.

Regards
Stanislaw
> 
> Signed-off-by: Ho Jie Feng <hjf3108@gmail.com>
> ---
>  drivers/net/wireless/ralink/rt2x00/rt2800lib.c |  8 ++++++++
>  drivers/net/wireless/ralink/rt2x00/rt2x00dev.c | 13 +++++++++++--
>  2 files changed, 19 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/wireless/ralink/rt2x00/rt2800lib.c b/drivers/net/wireless/ralink/rt2x00/rt2800lib.c
> index 9d88ee698b854..de234bcc7a065 100644
> --- a/drivers/net/wireless/ralink/rt2x00/rt2800lib.c
> +++ b/drivers/net/wireless/ralink/rt2x00/rt2800lib.c
> @@ -1116,6 +1116,14 @@ void rt2800_txdone_entry(struct queue_entry *entry, u32 status, __le32 *txwi,
>  		 */
>  		__set_bit(TXDONE_SUCCESS, &txdesc.flags);
>  		txdesc.retry = ((mcs > real_mcs) ? mcs - real_mcs : 0);
> +
> +		/*
> +		 * On RT3593 MCS16 falls back to MCS8, so a frame that was
> +		 * sent below MCS16 after a three stream rate skipped MCS9
> +		 * to MCS15.
> +		 */
> +		if (rt2x00_rt(rt2x00dev, RT3593) && mcs >= 16 && real_mcs < 16)
> +			txdesc.retry -= 7;
>  	} else {
>  		/*
>  		 * Transmission failed. The number of retries is
> diff --git a/drivers/net/wireless/ralink/rt2x00/rt2x00dev.c b/drivers/net/wireless/ralink/rt2x00/rt2x00dev.c
> index 4d94b7062f440..823785088a308 100644
> --- a/drivers/net/wireless/ralink/rt2x00/rt2x00dev.c
> +++ b/drivers/net/wireless/ralink/rt2x00/rt2x00dev.c
> @@ -329,10 +329,10 @@ static void rt2x00lib_fill_tx_status(struct rt2x00_dev *rt2x00dev,
>  	 * lowest rate was used.
>  	 */
>  	for (i = 0; i < retry_rates && i < IEEE80211_TX_MAX_RATES; i++) {
> -		tx_info->status.rates[i].idx = rate_idx - i;
> +		tx_info->status.rates[i].idx = rate_idx;
>  		tx_info->status.rates[i].flags = rate_flags;
>  
> -		if (rate_idx - i == 0) {
> +		if (rate_idx == 0) {
>  			/*
>  			 * The lowest rate (index 0) was used until the
>  			 * number of max retries was reached.
> @@ -340,8 +340,17 @@ static void rt2x00lib_fill_tx_status(struct rt2x00_dev *rt2x00dev,
>  			tx_info->status.rates[i].count = retry_rates - i;
>  			i++;
>  			break;
> +		} else if (rate_idx == 16) {
> +			/*
> +			 * TX_FBK_CFG_3S_0 makes MCS16 fall back to MCS8 on
> +			 * RT3593, the decrement below shifts it back to 8.
> +			 */
> +			if (rt2x00_rt(rt2x00dev, RT3593) &&
> +			    (rate_flags & IEEE80211_TX_RC_MCS))
> +				rate_idx = 9;
>  		}
>  		tx_info->status.rates[i].count = 1;
> +		rate_idx--;
>  	}
>  	if (i < (IEEE80211_TX_MAX_RATES - 1))
>  		tx_info->status.rates[i].idx = -1; /* terminate */
> -- 
> 2.53.0
>