linux-kernel - Re: [PATCH] drm/ingenic: Silence uninitialized-variable warning

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Message-ID: <20200719102354.GA20692@ravnborg.org>
Date:   Sun, 19 Jul 2020 12:23:54 +0200
From:   Sam Ravnborg <sam@...nborg.org>
To:     Paul Cercueil <paul@...pouillou.net>
Cc:     David Airlie <airlied@...ux.ie>, Daniel Vetter <daniel@...ll.ch>,
        od@...c.me, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/ingenic: Silence uninitialized-variable warning

Hi Paul.

On Sun, Jul 19, 2020 at 11:38:34AM +0200, Paul Cercueil wrote:
> Silence compiler warning about used but uninitialized 'ipu_state'
> variable. In practice, the variable would never be used when
> uninitialized, but the compiler cannot know that 'priv->ipu_plane' will
> always be NULL if CONFIG_INGENIC_IPU is disabled.
> 
> Silence the warning by initializing the value to NULL.
> 
> Signed-off-by: Paul Cercueil <paul@...pouillou.net>
Patch looks good. Had to dig into the code to understand the
change to the no_vblank flag.
So:
Reviewed-by: Sam Ravnborg <sam@...nborg.org>

I expect you to commit the patch.

Looking at the code I noticed that the return value of
drm_atomic_get_plane_state() is not checked.
Can you try to look into this.

	Sam

> ---
>  drivers/gpu/drm/ingenic/ingenic-drm-drv.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> index b6d946fbeaf5..ada990a7f911 100644
> --- a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> +++ b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> @@ -198,7 +198,7 @@ static int ingenic_drm_crtc_atomic_check(struct drm_crtc *crtc,
>  					 struct drm_crtc_state *state)
>  {
>  	struct ingenic_drm *priv = drm_crtc_get_priv(crtc);
> -	struct drm_plane_state *f1_state, *f0_state, *ipu_state;
> +	struct drm_plane_state *f1_state, *f0_state, *ipu_state = NULL;
>  	long rate;
>  
>  	if (!drm_atomic_crtc_needs_modeset(state))
> @@ -229,7 +229,7 @@ static int ingenic_drm_crtc_atomic_check(struct drm_crtc *crtc,
>  
>  		/* If all the planes are disabled, we won't get a VBLANK IRQ */
>  		priv->no_vblank = !f1_state->fb && !f0_state->fb &&
> -				  !(priv->ipu_plane && ipu_state->fb);
> +				  !(ipu_state && ipu_state->fb);
>  	}
>  
>  	return 0;
> -- 
> 2.27.0