linux-kernel - Re: drivers/gpu/drm/gma500/mdfld_intel_display.c:102:37: warning: bitwise comparison always evaluates to false [-Wtautological-compare]

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Message-ID: <87mv4gj2t5.fsf@intel.com>
Date:   Tue, 24 Oct 2017 12:46:46 +0300
From:   Jani Nikula <jani.nikula@...ux.intel.com>
To:     David Binderman <dcb314@...mail.com>,
        "patrik.r.jakobsson\@gmail.com" <patrik.r.jakobsson@...il.com>,
        "airlied\@linux.ie" <airlied@...ux.ie>,
        "dri-devel\@lists.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: drivers/gpu/drm/gma500/mdfld_intel_display.c:102:37: warning: bitwise comparison always evaluates to false [-Wtautological-compare]

On Tue, 24 Oct 2017, David Binderman <dcb314@...mail.com> wrote:
> Hello there,
>
>
> Code I looked at is in linux-4.14-rc6, released 20171023, so reasonably
>
> up to date.
>
>
> I did a further check on github.com/torvalds/linux and the code
>
> looks wrong there, too.
>
>
> So I don't see the fix you mentioned in either of the places I looked.

It's in drm-next branch of [1] heading for v4.15. Please see MAINTAINERS
in the kernel source root for all the trees.

BR,
Jani.


[1] https://cgit.freedesktop.org/~airlied/linux/


>
>
> Regards
>
>
> David Binderman
>
> ________________________________
> From: Jani Nikula <jani.nikula@...ux.intel.com>
> Sent: 24 October 2017 08:54
> To: David Binderman; patrik.r.jakobsson@...il.com; airlied@...ux.ie; dri-devel@...ts.freedesktop.org; linux-kernel@...r.kernel.org
> Subject: Re: drivers/gpu/drm/gma500/mdfld_intel_display.c:102:37: warning: bitwise comparison always evaluates to false [-Wtautological-compare]
>
> On Mon, 23 Oct 2017, David Binderman <dcb314@...mail.com> wrote:
>> Hello there,
>>
>> Source code is
>>
>>         if ((temp & PIPEACONF_PIPE_STATE) == 1)
>>             break;
>>
>> but
>>
>> $ fgrep PIPEACONF_PIPE_STATE `find drivers/gpu/drm/gma500 -name \*.h -print`
>> drivers/gpu/drm/gma500/psb_intel_reg.h:#define PIPEACONF_PIPE_STATE           (1 << 30)
>> $
>>
>> Suggest new code
>>
>>         if ((temp & PIPEACONF_PIPE_STATE) != 0)
>>             break;
>
> Suggest looking at latest sources. ;)
>
> Fixed by 67a3b63a54cb ("drm: gma500: fix logic error").
>
> BR,
> Jani.
>
> --
> Jani Nikula, Intel Open Source Technology Center

-- 
Jani Nikula, Intel Open Source Technology Center