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

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Date:   Mon, 30 Oct 2023 12:53:58 -0400
From:   Aurabindo Pillai <aurabindo.pillai@....com>
To:     José Pekkarinen <jose.pekkarinen@...hound.fi>
Cc:     harry.wentland@....com, sunpeng.li@....com,
        Rodrigo.Siqueira@....com, skhan@...uxfoundation.org,
        alexander.deucher@....com, christian.koenig@....com,
        Xinhui.Pan@....com, airlied@...il.com, daniel@...ll.ch,
        dillon.varone@....com, Jun.Lei@....com, george.shen@....com,
        samson.tam@....com, SyedSaaem.Rizvi@....com,
        amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org,
        linux-kernel-mentees@...ts.linuxfoundation.org
Subject: Re: [PATCH] drm/amd/display: remove redundant check



On 2023-10-30 12:26, José Pekkarinen wrote:
> On 2023-10-30 15:52, Aurabindo Pillai wrote:
>> On 10/29/2023 8:44 AM, 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)
>>>
>>> Signed-off-by: José Pekkarinen <jose.pekkarinen@...hound.fi>
>>> ---
>>>   .../drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c   | 4 ----
>>>   1 file changed, 4 deletions(-)
>>>
>>> diff --git 
>>> a/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c 
>>> b/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
>>> index ecea008f19d3..d940dfa5ae43 100644
>>> --- 
>>> a/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
>>> +++ 
>>> b/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
>>> @@ -4661,10 +4661,6 @@ void dml32_CalculateMinAndMaxPrefetchMode(
>>>       } else if (AllowForPStateChangeOrStutterInVBlankFinal == 
>>> dm_prefetch_support_uclk_fclk_and_stutter) {
>>>           *MinPrefetchMode = 0;
>>>           *MaxPrefetchMode = 0;
>>> -    } else if (AllowForPStateChangeOrStutterInVBlankFinal ==
>>> -            dm_prefetch_support_uclk_fclk_and_stutter_if_possible) {
>>> -        *MinPrefetchMode = 0;
>>> -        *MaxPrefetchMode = 3;
>>>       } else {
>>>           *MinPrefetchMode = 0;
>>>           *MaxPrefetchMode = 3;
>>
>> What tree did you use to generate the patch? On amd-staging-drm-next,
>> MaxPrefetchMode is 0 for the second last branch, which is the correct
>> one, so this patch isnt needed.
> 
>      I'm using the stable tree, sorry, if it is out of
> date just ignore it then.
> 
>      Thanks!
> 
>      José.
Actually, you're right - the patch's limited context mislead me, sorry.
But please add the following tag and sent it to stable@...r.kernel.org 
instead:

Fixes: 974ce181 ("drm/amd/display: Add check for PState change in DCN32")