[PATCH wireless-next v2 2/4] wifi: rtw88: rtw8822c: use sign_extend32 for DAC IQ validation

[Arsenii Pashchenko]

Leverage the kernel's native sign_extend32() macro to properly
interpret the 10-bit raw values from hardware registers as signed
32-bit (s10) integers covering the [-512, 511] range.

This allows us to completely rewrite rtw8822c_dac_iq_check() to use
a simple, clean amplitude boundary check instead of complex, nested
unsigned boundary conditions. Drop the temporary u32 casts inside
the check and sampling routines.

Signed-off-by: Arsenii Pashchenko <ulijg308@xxxxxxxxx>
---
 drivers/net/wireless/realtek/rtw88/rtw8822c.c | 24 +++++++++----------
 1 file changed, 11 insertions(+), 13 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtw88/rtw8822c.c b/drivers/net/wireless/realtek/rtw88/rtw8822c.c
index 896e3e7b9..d06986d09 100644
--- a/drivers/net/wireless/realtek/rtw88/rtw8822c.c
+++ b/drivers/net/wireless/realtek/rtw88/rtw8822c.c
@@ -3,6 +3,7 @@
  */
 
 #include <linux/module.h>
+#include <linux/bitops.h>
 #include "main.h"
 #include "coex.h"
 #include "fw.h"
@@ -277,18 +278,15 @@ static u32 rtw8822c_get_path_read_addr(u8 path)
 	return base_addr;
 }
 
-static bool rtw8822c_dac_iq_check(struct rtw_dev *rtwdev, s32 value_s32)
+static bool rtw8822c_dac_iq_check(struct rtw_dev *rtwdev, s32 value)
 {
-	u32 value = (u32)value_s32;
-	bool ret = true;
 
-	if ((value >= 0x200 && (0x400 - value) > 0x64) ||
-	    (value < 0x200 && value > 0x64)) {
-		ret = false;
+	if (value > 100 || value < -100) {
 		rtw_dbg(rtwdev, RTW_DBG_RFK, "[DACK] Error overflow\n");
+		return false;
 	}
 
-	return ret;
+	return true;
 }
 
 static void rtw8822c_dac_cal_iq_sample(struct rtw_dev *rtwdev, s32 *iv, s32 *qv)
@@ -299,8 +297,8 @@ static void rtw8822c_dac_cal_iq_sample(struct rtw_dev *rtwdev, s32 *iv, s32 *qv)
 	while (i < DACK_SN_8822C && cnt < 10000) {
 		cnt++;
 		temp = rtw_read32_mask(rtwdev, 0x2dbc, 0x3fffff);
-		iv[i] = (s32)((temp & 0x3ff000) >> 12);
-		qv[i] = (s32)(temp & 0x3ff);
+		iv[i] = sign_extend32((temp & 0x3ff000) >> 12, 9);
+		qv[i] = sign_extend32(temp & 0x3ff, 9);
 
 		if (rtw8822c_dac_iq_check(rtwdev, iv[i]) &&
 		    rtw8822c_dac_iq_check(rtwdev, qv[i]))
@@ -352,11 +350,11 @@ static void rtw8822c_dac_cal_iq_search(struct rtw_dev *rtwdev,
 
 		if (i_delta > 5 || q_delta > 5) {
 			temp = rtw_read32_mask(rtwdev, 0x2dbc, 0x3fffff);
-			iv[0] = (s32)((temp & 0x3ff000) >> 12);
-			qv[0] = (s32)(temp & 0x3ff);
+			iv[0] = sign_extend32((temp & 0x3ff000) >> 12, 9);
+			qv[0] = sign_extend32(temp & 0x3ff, 9);
 			temp = rtw_read32_mask(rtwdev, 0x2dbc, 0x3fffff);
-			iv[DACK_SN_8822C - 1] = (s32)((temp & 0x3ff000) >> 12);
-			qv[DACK_SN_8822C - 1] = (s32)(temp & 0x3ff);
+			iv[DACK_SN_8822C - 1] = sign_extend32((temp & 0x3ff000) >> 12, 9);
+			qv[DACK_SN_8822C - 1] = sign_extend32(temp & 0x3ff, 9);
 		} else {
 			break;
 		}
-- 
2.55.0