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Subject: Re: [PATCH] drm/amd/display: Fix unsigned variable compared to less
 than zero
To:     "Gustavo A. R. Silva" <gustavo@embeddedor.com>,
        Harry Wentland <harry.wentland@amd.com>,
        Leo Li <sunpeng.li@amd.com>,
        Alex Deucher <alexander.deucher@amd.com>,
        =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>,
        "David (ChunMing) Zhou" <David1.Zhou@amd.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Mikita Lipski <mikita.lipski@amd.com>,
        Lyude Paul <lyude@redhat.com>,
        Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Cc:     amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org
References: <20191111172543.GA31748@embeddedor>
From:   Mikita Lipski <mlipski@amd.com>
Organization: AMD
Message-ID: <b5b41653-3536-b0f0-2f49-2c010370ec99@amd.com>
Date:   Mon, 11 Nov 2019 12:46:32 -0500
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Thanks for catching it!

Reviewed-by: Mikita Lipski <mikita.lipski@amd.com>


On 11.11.2019 12:25, Gustavo A. R. Silva wrote:
> Currenly, the error check below on variable*vcpi_slots*  is always
> false because it is a uint64_t type variable, hence, the values
> this variable can hold are never less than zero:
> 
> drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c:
> 4870         if (dm_new_connector_state->vcpi_slots < 0) {
> 4871                 DRM_DEBUG_ATOMIC("failed finding vcpi slots: %d\n", (int)dm_new_connector_stat     e->vcpi_slots);
> 4872                 return dm_new_connector_state->vcpi_slots;
> 4873         }
> 
> Fix this by making*vcpi_slots*  of int type
> 
> Addresses-Coverity: 1487838 ("Unsigned compared against 0")
> Fixes: b4c578f08378 ("drm/amd/display: Add MST atomic routines")
> Signed-off-by: Gustavo A. R. Silva<gustavo@embeddedor.com>
> ---
>   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
> index 6db07e9e33ab..a8fc90a927d6 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
> @@ -403,7 +403,7 @@ struct dm_connector_state {
>   	bool underscan_enable;
>   	bool freesync_capable;
>   	uint8_t abm_level;
> -	uint64_t vcpi_slots;
> +	int vcpi_slots;
>   	uint64_t pbn;
>   };
>   
> -- 2.23.0

-- 
Thanks,
Mikita Lipski
Software Engineer, AMD
mikita.lipski@amd.com