Re: [PATCH wireless-next v2 3/5] b43: N-PHY: fix rev3+ RSSI calibration

[Alessio Ferri <alessio.ferri@mythread.it>]

Il giorno Fri,  6 Nov 2026 22:15:14 +0100
Luca Casati <luk00casati@gmail.com> ha scritto:

> Three bugs in b43_nphy_rev3_rssi_cal():
> 
> - On rev7+ the selected VCM was written using the loop counter (8
> after the search loop) instead of vcm_final; the 3-bit field turned
> that into VCM 0 on every rev7+ PHY.
> - The distance used I*I + Q*I instead of I*I + Q*Q (brcmsmac
>   wlc_phy_rssi_cal_nphy_rev3()).
> - Negative W1/W2 offsets were rounded as -(abs(x + 4) / 8) instead of
>   -((abs(x) + 4) / 8).
> 
> mmiotraces: https://github.com/Luca00casati/b43patch/blob/755c2d8/traces/excerpts/patch3-rssi-vcm.txt
> 
> Found and fixed with the help of an AI coding assistant (Claude Opus
> 5.5), by comparing mmiotraces of b43 and wl on the same card.
> 
> Signed-off-by: Luca Casati <luk00casati@gmail.com>
> ---
>  drivers/net/wireless/broadcom/b43/phy_n.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/wireless/broadcom/b43/phy_n.c
> b/drivers/net/wireless/broadcom/b43/phy_n.c index
> 6b0140f05..36c07d891 100644 ---
> a/drivers/net/wireless/broadcom/b43/phy_n.c +++
> b/drivers/net/wireless/broadcom/b43/phy_n.c @@ -2167,7 +2167,7 @@
> static void b43_nphy_rev3_rssi_cal(struct b43_wldev *dev) continue;
>  			for (vcm = 0; vcm < 8; vcm++) {
>  				currd = results[vcm][i] *
> results[vcm][i] +
> -					results[vcm][i + 1] *
> results[vcm][i];
> +					results[vcm][i + 1] *
> results[vcm][i + 1]; if (currd < mind) {
>  					mind = currd;
>  					minvcm = vcm;

Ok, in the original there was probably a copy paste error.

> @@ -2184,7 +2184,7 @@ static void b43_nphy_rev3_rssi_cal(struct
> b43_wldev *dev) b43_radio_maskset(dev,
>  					  core ?
> R2057_NB_MASTER_CORE1 : R2057_NB_MASTER_CORE0,
> -					  ~R2057_VCM_MASK, vcm);
> +					  ~R2057_VCM_MASK,
> vcm_final); else
>  			b43_radio_maskset(dev, r |
> B2056_RX_RSSI_MISC, 0xE3, vcm_final << 2);

ok, vcm is clearly wrong, the loop is meant select vcm_final, vcm
simply hold the last loop index.

> @@ -2219,7 +2219,7 @@ static void b43_nphy_rev3_rssi_cal(struct
> b43_wldev *dev) if (j / 2 == core) {
>  					offset[j] = 232 -
> poll_results[j]; if (offset[j] < 0)
> -						offset[j] =
> -(abs(offset[j] + 4) / 8);
> +						offset[j] =
> -((abs(offset[j]) + 4) / 8); else
>  						offset[j] =
> (offset[j] + 4) / 8; b43_nphy_scale_offset_rssi(dev, 0,

Fine

This change the code also for other revs, correct?

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