linux-kernel - Re: [PATCH] drm/amd/display: remove redundant check

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Message-ID: <1175edcbdf0d0a55d39a87f220259528@foxhound.fi>
Date:   Tue, 31 Oct 2023 14:32:02 +0200
From:   José Pekkarinen <jose.pekkarinen@...hound.fi>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     harry.wentland@....com, sunpeng.li@....com,
        Rodrigo.Siqueira@....com, skhan@...uxfoundation.org,
        dillon.varone@....com,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        dri-devel@...ts.freedesktop.org, Xinhui.Pan@....com,
        linux-kernel@...r.kernel.org, samson.tam@....com,
        SyedSaaem.Rizvi@....com, aurabindo.pillai@....com,
        stable@...r.kernel.org, daniel@...ll.ch, george.shen@....com,
        alexander.deucher@....com, Jun.Lei@....com, airlied@...il.com,
        christian.koenig@....com
Subject: Re: [PATCH] drm/amd/display: remove redundant check

On 2023-10-31 14:20, Greg KH wrote:
> On Tue, Oct 31, 2023 at 01:42:17PM +0200, José Pekkarinen wrote:
>> On 2023-10-31 07:48, Greg KH wrote:
>> > On Mon, Oct 30, 2023 at 07:17:48PM +0200, José Pekkarinen wrote:
>> > > This patch addresses the following warning spotted by
>> > > using coccinelle where the case checked does the same
>> > > than the else case.
>> > >
>> > > drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c:4664:8-10:
>> > > WARNING: possible condition with no effect (if == else)
>> > >
>> > > Fixes: 974ce181 ("drm/amd/display: Add check for PState change in
>> > > DCN32")
>> > >
>> > > Cc: stable@...r.kernel.org
>> >
>> > Why is this relevant for stable?
>> 
>>     Hi,
>> 
>>     I was asked to send it for stable because this code
>> looks different in amd-staging-drm-next, see here.
>> 
>> https://gitlab.freedesktop.org/agd5f/linux/-/blob/amd-staging-drm-next/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c#L4661
> 
> I don't know what I am looking at, sorry.
> 
>>     Feel free to let me know if this is wrong, or if I
>> need to review some other guidelines I may have missed.
> 
> Please see the list of rules for stable patches:
>     
> https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
> 
> Does "remove code that does nothing" fit here?

     Yep, it is a trivial fix which compilers should be able
to optimize, so no real benefit to the user. Sorry Greg!

     José.