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Date:   Tue, 22 Oct 2019 10:37:25 +0200
From:   Daniel Vetter <daniel@ffwll.ch>
To:     Benjamin Gaignard <benjamin.gaignard@st.com>
Cc:     airlied@linux.ie, daniel@ffwll.ch, ville.syrjala@linux.intel.com,
        linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH v2] drm: atomic helper: fix W=1 warnings
Message-ID: <20191022083725.GW11828@phenom.ffwll.local>
Mail-Followup-To: Benjamin Gaignard <benjamin.gaignard@st.com>,
        airlied@linux.ie, ville.syrjala@linux.intel.com,
        linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org
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On Tue, Oct 08, 2019 at 02:42:54PM +0200, Benjamin Gaignard wrote:
> Few for_each macro set variables that are never used later which led
> to generate unused-but-set-variable warnings.
> Add (void)(foo) inside the macros to remove these warnings
> 
> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>

OCD in me would lean towards annotating all of them, unconditionally, and
be done. But I guess this works too. Either way:

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> ---
>  include/drm/drm_atomic.h | 17 ++++++++++++++---
>  1 file changed, 14 insertions(+), 3 deletions(-)
> 
> diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
> index 927e1205d7aa..b6c73fd9f55a 100644
> --- a/include/drm/drm_atomic.h
> +++ b/include/drm/drm_atomic.h
> @@ -693,6 +693,7 @@ void drm_state_dump(struct drm_device *dev, struct drm_printer *p);
>  	     (__i)++)								\
>  		for_each_if ((__state)->connectors[__i].ptr &&			\
>  			     ((connector) = (__state)->connectors[__i].ptr,	\
> +			     (void)(connector) /* Only to avoid unused-but-set-variable warning */, \
>  			     (old_connector_state) = (__state)->connectors[__i].old_state,	\
>  			     (new_connector_state) = (__state)->connectors[__i].new_state, 1))
>  
> @@ -714,6 +715,7 @@ void drm_state_dump(struct drm_device *dev, struct drm_printer *p);
>  	     (__i)++)								\
>  		for_each_if ((__state)->connectors[__i].ptr &&			\
>  			     ((connector) = (__state)->connectors[__i].ptr,	\
> +			     (void)(connector) /* Only to avoid unused-but-set-variable warning */, \
>  			     (old_connector_state) = (__state)->connectors[__i].old_state, 1))
>  
>  /**
> @@ -734,7 +736,9 @@ void drm_state_dump(struct drm_device *dev, struct drm_printer *p);
>  	     (__i)++)								\
>  		for_each_if ((__state)->connectors[__i].ptr &&			\
>  			     ((connector) = (__state)->connectors[__i].ptr,	\
> -			     (new_connector_state) = (__state)->connectors[__i].new_state, 1))
> +			     (void)(connector) /* Only to avoid unused-but-set-variable warning */, \
> +			     (new_connector_state) = (__state)->connectors[__i].new_state, \
> +			     (void)(new_connector_state) /* Only to avoid unused-but-set-variable warning */, 1))
>  
>  /**
>   * for_each_oldnew_crtc_in_state - iterate over all CRTCs in an atomic update
> @@ -754,7 +758,9 @@ void drm_state_dump(struct drm_device *dev, struct drm_printer *p);
>  	     (__i)++)							\
>  		for_each_if ((__state)->crtcs[__i].ptr &&		\
>  			     ((crtc) = (__state)->crtcs[__i].ptr,	\
> +			      (void)(crtc) /* Only to avoid unused-but-set-variable warning */, \
>  			     (old_crtc_state) = (__state)->crtcs[__i].old_state, \
> +			     (void)(old_crtc_state) /* Only to avoid unused-but-set-variable warning */, \
>  			     (new_crtc_state) = (__state)->crtcs[__i].new_state, 1))
>  
>  /**
> @@ -793,7 +799,9 @@ void drm_state_dump(struct drm_device *dev, struct drm_printer *p);
>  	     (__i)++)							\
>  		for_each_if ((__state)->crtcs[__i].ptr &&		\
>  			     ((crtc) = (__state)->crtcs[__i].ptr,	\
> -			     (new_crtc_state) = (__state)->crtcs[__i].new_state, 1))
> +			     (void)(crtc) /* Only to avoid unused-but-set-variable warning */, \
> +			     (new_crtc_state) = (__state)->crtcs[__i].new_state, \
> +			     (void)(new_crtc_state) /* Only to avoid unused-but-set-variable warning */, 1))
>  
>  /**
>   * for_each_oldnew_plane_in_state - iterate over all planes in an atomic update
> @@ -813,6 +821,7 @@ void drm_state_dump(struct drm_device *dev, struct drm_printer *p);
>  	     (__i)++)							\
>  		for_each_if ((__state)->planes[__i].ptr &&		\
>  			     ((plane) = (__state)->planes[__i].ptr,	\
> +			      (void)(plane) /* Only to avoid unused-but-set-variable warning */, \
>  			      (old_plane_state) = (__state)->planes[__i].old_state,\
>  			      (new_plane_state) = (__state)->planes[__i].new_state, 1))
>  
> @@ -873,7 +882,9 @@ void drm_state_dump(struct drm_device *dev, struct drm_printer *p);
>  	     (__i)++)							\
>  		for_each_if ((__state)->planes[__i].ptr &&		\
>  			     ((plane) = (__state)->planes[__i].ptr,	\
> -			      (new_plane_state) = (__state)->planes[__i].new_state, 1))
> +			      (void)(plane) /* Only to avoid unused-but-set-variable warning */, \
> +			      (new_plane_state) = (__state)->planes[__i].new_state, \
> +			      (void)(new_plane_state) /* Only to avoid unused-but-set-variable warning */, 1))
>  
>  /**
>   * for_each_oldnew_private_obj_in_state - iterate over all private objects in an atomic update
> -- 
> 2.15.0
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch