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Date:   Fri, 23 Jun 2023 18:46:15 +0300
From:   Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To:     Geert Uytterhoeven <geert+renesas@glider.be>
Cc:     Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        Magnus Damm <magnus.damm@gmail.com>,
        dri-devel@lists.freedesktop.org, linux-renesas-soc@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 17/39] drm: renesas: shmobile: Use
 drmm_universal_plane_alloc()
Message-ID: <20230623154615.GU2112@pendragon.ideasonboard.com>
References: <cover.1687423204.git.geert+renesas@glider.be>
 <9af0b0e18c6f3ce3348cc728f177bf466e30e66a.1687423204.git.geert+renesas@glider.be>
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In-Reply-To: <9af0b0e18c6f3ce3348cc728f177bf466e30e66a.1687423204.git.geert+renesas@glider.be>
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Hi Geert,

Thank you for the patch.

On Thu, Jun 22, 2023 at 11:21:29AM +0200, Geert Uytterhoeven wrote:
> According to the comments for drm_universal_plane_init(), the plane
> structure should not be allocated with devm_kzalloc().
> 
> Fix lifetime issues by using drmm_universal_plane_alloc() instead.
> 
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> ---
> Plane (and connector) structures are still allocated with devm_kzalloc()
> in several other drivers...
> ---
>  .../drm/renesas/shmobile/shmob_drm_plane.c    | 24 ++++++-------------
>  1 file changed, 7 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/gpu/drm/renesas/shmobile/shmob_drm_plane.c b/drivers/gpu/drm/renesas/shmobile/shmob_drm_plane.c
> index 0b2ab153e9ae76df..1fb68b5fe915b8dc 100644
> --- a/drivers/gpu/drm/renesas/shmobile/shmob_drm_plane.c
> +++ b/drivers/gpu/drm/renesas/shmobile/shmob_drm_plane.c
> @@ -176,16 +176,9 @@ static int shmob_drm_plane_disable(struct drm_plane *plane,
>  	return 0;
>  }
>  
> -static void shmob_drm_plane_destroy(struct drm_plane *plane)
> -{
> -	drm_plane_force_disable(plane);
> -	drm_plane_cleanup(plane);

drm_plane_cleanup() will still be called from
drmm_universal_plane_alloc_release(), but drm_plane_force_disable()
won't. Is this an issue ? This should be documented in the commit
message.

> -}
> -
>  static const struct drm_plane_funcs shmob_drm_plane_funcs = {
>  	.update_plane = shmob_drm_plane_update,
>  	.disable_plane = shmob_drm_plane_disable,
> -	.destroy = shmob_drm_plane_destroy,
>  };
>  
>  static const uint32_t formats[] = {
> @@ -204,19 +197,16 @@ static const uint32_t formats[] = {
>  int shmob_drm_plane_create(struct shmob_drm_device *sdev, unsigned int index)
>  {
>  	struct shmob_drm_plane *splane;
> -	int ret;
>  
> -	splane = devm_kzalloc(sdev->dev, sizeof(*splane), GFP_KERNEL);
> -	if (splane == NULL)
> -		return -ENOMEM;
> +	splane = drmm_universal_plane_alloc(sdev->ddev, struct shmob_drm_plane,
> +					    plane, 1, &shmob_drm_plane_funcs,
> +					    formats, ARRAY_SIZE(formats), NULL,
> +					    DRM_PLANE_TYPE_OVERLAY, NULL);
> +	if (IS_ERR(splane))
> +		return PTR_ERR(splane);
>  
>  	splane->index = index;
>  	splane->alpha = 255;
>  
> -	ret = drm_universal_plane_init(sdev->ddev, &splane->plane, 1,
> -				       &shmob_drm_plane_funcs,
> -				       formats, ARRAY_SIZE(formats), NULL,
> -				       DRM_PLANE_TYPE_OVERLAY, NULL);
> -
> -	return ret;
> +	return 0;
>  }

-- 
Regards,

Laurent Pinchart