[PATCH wireless-next 1/5] b43: N-PHY: fix the TX tone sample table

[Luca Casati <luk00casati@gmail.com>]

b43_nphy_load_samples() masked with (0x3FF << 10) instead of shifting
the masked I value, and b43_nphy_gen_load_samples() fed
cordic_calc_iq() a 16.16 fixed-point angle (CORDIC_FIXED() of a value
already shifted by 16) held in a u16, while the function takes whole
degrees. Together the sample table ended up all zeros, so every
calibration that plays a test tone (TX IQ/LO, RX IQ) ran without a
signal.

Compute the rotation in whole degrees as brcmsmac does and fix the
precedence.

Tested on a BCM43228 (N-PHY rev 16, radio 2057 rev 9).

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 | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/broadcom/b43/phy_n.c b/drivers/net/wireless/broadcom/b43/phy_n.c
index bbc30cbad..66565c14e 100644
--- a/drivers/net/wireless/broadcom/b43/phy_n.c
+++ b/drivers/net/wireless/broadcom/b43/phy_n.c
@@ -1515,7 +1515,7 @@ static int b43_nphy_load_samples(struct b43_wldev *dev,
 		b43_nphy_stay_in_carrier_search(dev, 1);
 
 	for (i = 0; i < len; i++) {
-		data[i] = (samples[i].i & 0x3FF << 10);
+		data[i] = (samples[i].i & 0x3FF) << 10;
 		data[i] |= samples[i].q & 0x3FF;
 	}
 	b43_ntab_write_bulk(dev, B43_NTAB32(17, 0), len, data);
@@ -1531,7 +1531,8 @@ static u16 b43_nphy_gen_load_samples(struct b43_wldev *dev, u32 freq, u16 max,
 					bool test)
 {
 	int i;
-	u16 bw, len, rot, angle;
+	u16 bw, len;
+	s32 rot, angle;		/* whole degrees, as cordic_calc_iq() wants */
 	struct cordic_iq *samples;
 
 	bw = b43_is_40mhz(dev) ? 40 : 20;
@@ -1554,11 +1555,11 @@ static u16 b43_nphy_gen_load_samples(struct b43_wldev *dev, u32 freq, u16 max,
 		b43err(dev->wl, "allocation for samples generation failed\n");
 		return 0;
 	}
-	rot = (((freq * 36) / bw) << 16) / 100;
+	rot = ((freq * 36) / bw) / 100;
 	angle = 0;
 
 	for (i = 0; i < len; i++) {
-		samples[i] = cordic_calc_iq(CORDIC_FIXED(angle));
+		samples[i] = cordic_calc_iq(angle);
 		angle += rot;
 		samples[i].q = CORDIC_FLOAT(samples[i].q * max);
 		samples[i].i = CORDIC_FLOAT(samples[i].i * max);
-- 
2.43.0