linux-kernel - Re: [PATCH] drm/amd/display: remove unreachable code

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Message-ID: <e95a5040-6cd2-3b74-1b65-50bc7c6b6ddb@gmail.com>
Date:   Fri, 12 Aug 2022 14:36:56 -0300
From:   Tales Lelo da Aparecida <tales.aparecida@...il.com>
To:     Jiapeng Chong <jiapeng.chong@...ux.alibaba.com>
Cc:     airlied@...ux.ie, Xinhui.Pan@....com,
        Abaci Robot <abaci@...ux.alibaba.com>,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        amd-gfx@...ts.freedesktop.org, daniel@...ll.ch,
        christian.koenig@....com, alexander.deucher@....com
Subject: Re: [PATCH] drm/amd/display: remove unreachable code

Hi,

On 12/08/2022 00:19, Jiapeng Chong wrote:
> drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn32/display_mode_vba_util_32.c:1658 dml32_TruncToValidBPP() warn: ignoring unreachable code.
> 
> Link: https://bugzilla.openanolis.cn/show_bug.cgi?id=1894
> Reported-by: Abaci Robot <abaci@...ux.alibaba.com>
> Signed-off-by: Jiapeng Chong <jiapeng.chong@...ux.alibaba.com>
> ---
>   .../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 05fc14a47fba..0758e1da55a9 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
> @@ -1654,10 +1654,6 @@ double dml32_TruncToValidBPP(
>   		else
>   			return DesiredBPP;
>   	}
> -
> -	*RequiredSlots = dml_ceil(DesiredBPP / MaxLinkBPP * 64, 1);
> -
> -	return BPP_INVALID;
>   } // TruncToValidBPP
>   
>   double dml32_RequiredDTBCLK(

Seems correct.

Reviewed-by: Tales Aparecida <tales.aparecida@...il.com>

I feel like RequiredSlots is not actually used anywhere in the code, 
just passed around dml32_TruncToValidBPP() and 
dml32_CalculateOutputLink(). I've looked for any mentions of it in the 
mailing list, but could not find anything that implied it's part of 
ground working. I wonder if it's something outside the Linux tree for 
other platforms or related to HW gospel.