linux-kernel - [PATCH] staging: r8188eu: remove local BIT macro

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Date:   Sat, 19 Mar 2022 19:03:42 +0100
From:   Martin Kaiser <martin@...ser.cx>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Larry Finger <Larry.Finger@...inger.net>,
        Phillip Potter <phil@...lpotter.co.uk>,
        Michael Straube <straube.linux@...il.com>,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org,
        Martin Kaiser <martin@...ser.cx>
Subject: [PATCH] staging: r8188eu: remove local BIT macro

The r8188eu driver defines a local BIT(x) macro. Remove this local macro
and use the one from include/linux/bits.h.

The global BIT macro returns an unsigned long value, the removed local
BIT macro used a signed int.

DYNAMIC_BB_DYNAMIC_TXPWR is defined as BIT(2), ~DYNAMIC_BB_DYNAMIC_TXPWR
is passed to Switch_DM_Func as a u32 parameter. We need a cast in this
case as ~DYNAMIC_BB_DYNAMIC_TXPWR is a 64-bit value on x86_64 systems.

Signed-off-by: Martin Kaiser <martin@...ser.cx>
---

Dear all,

this is the next attempt to get this right. I'm not sure if it should be
labeled v3. Greg accepted all other patches of the "some rx cleanups"
series, so I'm sending this as a single patch, starting at v1 again.

Thanks to Greg and Dan for the feedback, I see that ((u32)BIT(2)) is not
different from BIT(2) without the cast. Making the cast where
DYNAMIC_BB_DYNAMIC_TXPWR is used is the better option.

It seems that (u32)(~DYNAMIC_BB_DYNAMIC_TXPWR) and
~(u32)DYNAMIC_BB_DYNAMIC_TXPWR do the same thing and it's ok to invert
first and to cast afterwards. According to the C99 standard, a 64-bit
unsigned int is cast to u32 by repeatedly adding U32_MAX + 1 until the
result fits into a u32 - or simply by cutting off the upper 32bit.

BTW the previous rtl8188eu driver used
Switch_DM_Func(padapter, (u32)(~DYNAMIC_BB_DYNAMIC_TXPWR), false);
as well.

Thanks,
Martin

 drivers/staging/r8188eu/core/rtw_wlan_util.c | 4 ++--
 drivers/staging/r8188eu/include/wifi.h       | 7 +------
 2 files changed, 3 insertions(+), 8 deletions(-)

diff --git a/drivers/staging/r8188eu/core/rtw_wlan_util.c b/drivers/staging/r8188eu/core/rtw_wlan_util.c
index 665b077190bc..f32401deae9a 100644
--- a/drivers/staging/r8188eu/core/rtw_wlan_util.c
+++ b/drivers/staging/r8188eu/core/rtw_wlan_util.c
@@ -1276,13 +1276,13 @@ void update_IOT_info(struct adapter *padapter)
 		pmlmeinfo->turboMode_cts2self = 0;
 		pmlmeinfo->turboMode_rtsen = 1;
 		/* disable high power */
-		Switch_DM_Func(padapter, (~DYNAMIC_BB_DYNAMIC_TXPWR), false);
+		Switch_DM_Func(padapter, (u32)(~DYNAMIC_BB_DYNAMIC_TXPWR), false);
 		break;
 	case HT_IOT_PEER_REALTEK:
 		/* rtw_write16(padapter, 0x4cc, 0xffff); */
 		/* rtw_write16(padapter, 0x546, 0x01c0); */
 		/* disable high power */
-		Switch_DM_Func(padapter, (~DYNAMIC_BB_DYNAMIC_TXPWR), false);
+		Switch_DM_Func(padapter, (u32)(~DYNAMIC_BB_DYNAMIC_TXPWR), false);
 		break;
 	default:
 		pmlmeinfo->turboMode_cts2self = 0;
diff --git a/drivers/staging/r8188eu/include/wifi.h b/drivers/staging/r8188eu/include/wifi.h
index c331be19ff83..299553351246 100644
--- a/drivers/staging/r8188eu/include/wifi.h
+++ b/drivers/staging/r8188eu/include/wifi.h
@@ -4,14 +4,9 @@
 #ifndef _WIFI_H_
 #define _WIFI_H_

+#include <linux/bits.h>
 #include <linux/ieee80211.h>

-#ifdef BIT
-/* error	"BIT define occurred earlier elsewhere!\n" */
-#undef BIT
-#endif
-#define BIT(x)	(1 << (x))
-
 #define WLAN_ETHHDR_LEN		14
 #define WLAN_HDR_A3_LEN		24
 #define WLAN_HDR_A3_QOS_LEN	26
-- 
2.30.2