Re: [PATCH wireless 4/4] wifi: mt76: mt7925: fix RCPI chain 3 mask in sta_poll RSSI extraction

[Ben Greear <greearb@candelatech.com>]

On 4/6/26 16:47, Joshua Klinesmith wrote:
> The fourth receive chain RCPI uses GENMASK(31, 14), an 18-bit mask
> spanning bits 14-31. It should be GENMASK(31, 24), an 8-bit mask
> for the fourth byte, consistent with the other three chains and
> with the RCPI3 definitions used elsewhere in the driver
> (MT_PRXV_RCPI3 and MT_TXS7_F0_RCPI_3 both use GENMASK(31, 24)).

Hello Joshua,

How much of this is AI driven?  As far as I know, mt7925 is a 2x2 chipset
at max.  So while the patch may be correct, it may also not matter in practice
and at least may not need to be backported into stable.  If it is a minor
cleanup that doesn't actually matter, that should be described more clearly
in the commit message?

Some of your patches are touching tricky parts of the code and making
subtle comparisons against how the vendor's driver is written.  How well has
this been tested and reviewed by a knowledgeable human in general?

Thanks,
Ben

> 
> On devices with fewer than 4 antenna chains, the corrupted value
> is masked out by antenna_mask in mt76_rx_signal(). On 4-chain
> devices, this produces incorrect ACK signal strength readings.
> 
> Fixes: c948b5da6bbe ("wifi: mt76: mt7925: add Mediatek Wi-Fi7 driver for mt7925 chips")
> Cc: stable@vger.kernel.org
> Signed-off-by: Joshua Klinesmith <joshuaklinesmith@gmail.com>
> ---
>   drivers/net/wireless/mediatek/mt76/mt7925/mac.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/mediatek/mt76/mt7925/mac.c b/drivers/net/wireless/mediatek/mt76/mt7925/mac.c
> index 6334019249..85e91ca84f 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt7925/mac.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt7925/mac.c
> @@ -144,7 +144,7 @@ static void mt7925_mac_sta_poll(struct mt792x_dev *dev)
>   		rssi[0] = to_rssi(GENMASK(7, 0), val);
>   		rssi[1] = to_rssi(GENMASK(15, 8), val);
>   		rssi[2] = to_rssi(GENMASK(23, 16), val);
> -		rssi[3] = to_rssi(GENMASK(31, 14), val);
> +		rssi[3] = to_rssi(GENMASK(31, 24), val);
>   
>   		mlink->ack_signal =
>   			mt76_rx_signal(msta->vif->phy->mt76->antenna_mask, rssi);

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com