linux-kernel - Re: [PATCH] net: wireless: rtlwifi: rtl8192de: hw.c: Cleaning up conjunction always evaluates to false

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Date:	Sat, 7 Jun 2014 17:24:19 +0200
From:	Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
To:	Peter Wu <peter@...ensteyn.nl>
Cc:	Larry Finger <Larry.Finger@...inger.net>,
	Chaoming Li <chaoming_li@...lsil.com.cn>,
	"John W. Linville" <linville@...driver.com>,
	linux-wireless@...r.kernel.org,
	Network Development <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] net: wireless: rtlwifi: rtl8192de: hw.c: Cleaning up
 conjunction always evaluates to false

Hi!

Yes, 0x3 was one of the most likely :)
But wanted someone who knows the code better would be heard.
All agreed? Then I do a new patch.

Looks like it is the same error in the files below, I'll fix them all them to.

rtl8192cu/hw.c:1363:    if ((bt_msr & 0xfc) == MSR_AP)
rtl8192ce/hw.c:1209:    if ((bt_msr & 0xfc) == MSR_AP)
rtl8188ee/hw.c:1234:    if ((bt_msr & 0xfc) == MSR_AP)
rtl8192de/hw.c:1131:    if ((bt_msr & 0xfc) == MSR_AP)


Best regards
Rickard Strandqvist


2014-06-07 17:02 GMT+02:00 Peter Wu <peter@...ensteyn.nl>:
> On Saturday 07 June 2014 16:30:19 Rickard Strandqvist wrote:
>> Expression '(X & 0xfc) == 0x3' is always false
>
> While this is true, I believe that some other mistake is made.
>
>> I chose to remove this code, because it will not make any difference.
>> But obviously it is rather a properly designed if statement that is needed.
>>
>> This was partly found using a static code analysis program called cppcheck.
>>
>> Signed-off-by: Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
>> ---
>>  drivers/net/wireless/rtlwifi/rtl8192de/hw.c |    5 +----
>>  1 file changed, 1 insertion(+), 4 deletions(-)
>>
>> diff --git a/drivers/net/wireless/rtlwifi/rtl8192de/hw.c b/drivers/net/wireless/rtlwifi/rtl8192de/hw.c
>> index 2b08671..a1520d5 100644
>> --- a/drivers/net/wireless/rtlwifi/rtl8192de/hw.c
>> +++ b/drivers/net/wireless/rtlwifi/rtl8192de/hw.c
>> @@ -1128,10 +1128,7 @@ static int _rtl92de_set_media_status(struct ieee80211_hw *hw,
>>       }
>>       rtl_write_byte(rtlpriv, REG_CR + 2, bt_msr);
>>       rtlpriv->cfg->ops->led_control(hw, ledaction);
>> -     if ((bt_msr & 0xfc) == MSR_AP)
>
> If you look a few lines up, then you see that bt_msr is OR-ed with MSR_AP
> for AP interfaces. The 0xfc should be 0x03, see other drivers for example:
>
> rtl8723ae/hw.c:1112:    if ((bt_msr & 0x03) == MSR_AP)
> rtl8723be/hw.c:1200:    if ((bt_msr & 0x03) == MSR_AP)
> rtl8192cu/hw.c:1363:    if ((bt_msr & 0xfc) == MSR_AP)
> rtl8192ce/hw.c:1209:    if ((bt_msr & 0xfc) == MSR_AP)
> rtl8188ee/hw.c:1234:    if ((bt_msr & 0xfc) == MSR_AP)
> rtl8192de/hw.c:1131:    if ((bt_msr & 0xfc) == MSR_AP)
>
>> -             rtl_write_byte(rtlpriv, REG_BCNTCFG + 1, 0x00);
>> -     else
>> -             rtl_write_byte(rtlpriv, REG_BCNTCFG + 1, 0x66);
>> +     rtl_write_byte(rtlpriv, REG_BCNTCFG + 1, 0x66);
>>       return 0;
>>  }
>
> Kind regards,
> Peter
>
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