linux-kernel - Re: [BUG ?] staging: rtl8723au: condition with no effect

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Message-ID: <wrfjd20y1gxp.fsf@redhat.com>
Date:	Sun, 14 Jun 2015 10:51:46 -0400
From:	Jes Sorensen <Jes.Sorensen@...hat.com>
To:	Nicholas Mc Guire <der.herr@...r.at>
Cc:	Nicholas Mc Guire <hofrat@...dl.org>,
	Larry Finger <Larry.Finger@...inger.net>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Roberta Dobrescu <roberta.dobrescu@...il.com>,
	Joe Perches <joe@...ches.com>,
	Daniele Alessandrelli <daniele.alessandrelli@...il.com>,
	Aleh Suprunovich <br@...amon.org>,
	linux-wireless@...r.kernel.org, devel@...verdev.osuosl.org,
	linux-kernel@...r.kernel.org
Subject: Re: [BUG ?] staging: rtl8723au: condition with no effect

Nicholas Mc Guire <der.herr@...r.at> writes:
> On Sat, 13 Jun 2015, Jes Sorensen wrote:
>
>> Nicholas Mc Guire <hofrat@...dl.org> writes:
>> > scanning for trivial bug-patters with coccinelle spatches returned:
>> > ./drivers/staging/rtl8723au/hal/rtl8723a_hal_init.c:1395
>> > 	WARNING: condition with no effect (if branch == else)
>> >
>> > drivers/staging/rtl8723au/hal/rtl8723a_hal_init.c - line numbers
>> > from 4.1-rc7
>> > 1395    if (bWithoutHWSM) {
>> > 1396            /* value16 |= (APDM_HOST | FSM_HSUS |/PFM_ALDN); */
>> > 1397            /*  2010/08/31 According to Filen description, we need to
>> > 1398                use HW to shut down 8051 automatically. */
>> > 1399            /*  Because suspend operation need the asistance of 8051
>> > 1400                to wait for 3ms. */
>> > 1401            value16 = APDM_HOST | AFSM_HSUS | PFM_ALDN;
>> > 1402    } else {
>> > 1403            value16 = APDM_HOST | AFSM_HSUS | PFM_ALDN;
>> > 1404    }
>> > 1405 
>> > 1406    rtl8723au_write16(padapter, REG_APS_FSMCO, value16);    /* 0x4802 */
>> >
>> > Not clear what the intent is but this looks like a typo/bug in the assigment
>> > of value16 as the condition here has no effect.
>> 
>> Doesn't look like a typo, looks like someone at some point had commented
>> out PFM_ALDN in the bWithoutHWSM case. Why they did that and then later
>> overrode it, I have no idea.
>>
> as far as its traceable in git log if == else was in there from the
> very beginning (including that comment) - both the if and else were
> updated in commit cffca68d7b2f ("staging: rtl8723au: _DisableAnalog(): Avoid
> zero-init variables unnecessaril") but without changing PFM_ALDN - as there
> are no comments to the meaning of these bits in the header file there is
> no way to really come up with a resonable patch. anyway its either wrong 
> settings or the condition should be removed.

There's a much longer history of this code going back to the vendor
origin - it shouldn't be removed unless we can get clarification from
them why that was.

Jes
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