linux-kernel - Re: [PATCH] drm/amd/display: Use NULL for pointer assignment in copy_stream_update_to

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Message-ID: <ec7313da-dcdd-8884-063f-bf0e8cc664dd@amd.com>
Date:   Mon, 25 Nov 2019 09:28:05 -0500
From:   Harry Wentland <hwentlan@....com>
To:     Nathan Chancellor <natechancellor@...il.com>,
        Harry Wentland <harry.wentland@....com>,
        Leo Li <sunpeng.li@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        "David (ChunMing) Zhou" <David1.Zhou@....com>
Cc:     Dmytro Laktyushkin <Dmytro.Laktyushkin@....com>,
        Rodrigo Siqueira <Rodrigo.Siqueira@....com>,
        Nikola Cornij <nikola.cornij@....com>,
        amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, clang-built-linux@...glegroups.com
Subject: Re: [PATCH] drm/amd/display: Use NULL for pointer assignment in
 copy_stream_update_to_stream

On 2019-11-23 2:36 p.m., Nathan Chancellor wrote:
> Clang warns:
> 
> ../drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc.c:1965:26: warning:
> expression which evaluates to zero treated as a null pointer constant of
> type 'struct dc_dsc_config *' [-Wnon-literal-null-conversion]
>                                 update->dsc_config = false;
>                                                      ^~~~~
> ../drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc.c:1971:25: warning:
> expression which evaluates to zero treated as a null pointer constant of
> type 'struct dc_dsc_config *' [-Wnon-literal-null-conversion]
>                         update->dsc_config = false;
>                                              ^~~~~
> 2 warnings generated.
> 
> Fixes: f6fe4053b91f ("drm/amd/display: Use a temporary copy of the current state when updating DSC config")
> Link: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FClangBuiltLinux%2Flinux%2Fissues%2F777&amp;data=02%7C01%7Charry.wentland%40amd.com%7Ceb5e55813307456cf7d608d7704c79c4%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C1%7C637101346080296409&amp;sdata=6HK3wWYMoILbiBisjoHkFwopV%2BuJYUh8wCDhMSvRQQ8%3D&amp;reserved=0
> Signed-off-by: Nathan Chancellor <natechancellor@...il.com>

Reviewed-by: Harry Wentland <harry.wentland@....com>

Harry

> ---
>  drivers/gpu/drm/amd/display/dc/core/dc.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/dc/core/dc.c b/drivers/gpu/drm/amd/display/dc/core/dc.c
> index c7db4f4810c6..2645d20e8c4c 100644
> --- a/drivers/gpu/drm/amd/display/dc/core/dc.c
> +++ b/drivers/gpu/drm/amd/display/dc/core/dc.c
> @@ -1962,13 +1962,13 @@ static void copy_stream_update_to_stream(struct dc *dc,
>  			if (!dc->res_pool->funcs->validate_bandwidth(dc, dsc_validate_context, true)) {
>  				stream->timing.dsc_cfg = old_dsc_cfg;
>  				stream->timing.flags.DSC = old_dsc_enabled;
> -				update->dsc_config = false;
> +				update->dsc_config = NULL;
>  			}
>  
>  			dc_release_state(dsc_validate_context);
>  		} else {
>  			DC_ERROR("Failed to allocate new validate context for DSC change\n");
> -			update->dsc_config = false;
> +			update->dsc_config = NULL;
>  		}
>  	}
>  }
>