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Date:   Fri, 7 Jun 2019 09:39:58 +0200
From:   Daniel Vetter <daniel@ffwll.ch>
To:     Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Cc:     Brian Starkey <brian.starkey@arm.com>,
        Liviu Dudau <liviu.dudau@arm.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        Haneen Mohammed <hamohammed.sa@gmail.com>,
        Simon Ser <contact@emersion.fr>,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] drm/vkms: Use index instead of 0 in possible crtc
Message-ID: <20190607073957.GB21222@phenom.ffwll.local>
Mail-Followup-To: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>,
        Brian Starkey <brian.starkey@arm.com>,
        Liviu Dudau <liviu.dudau@arm.com>,
        Haneen Mohammed <hamohammed.sa@gmail.com>,
        Simon Ser <contact@emersion.fr>, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org
References: <cover.1559860606.git.rodrigosiqueiramelo@gmail.com>
 <e3bc263b273d91182e0577ed820b1c4f096834ec.1559860606.git.rodrigosiqueiramelo@gmail.com>
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On Thu, Jun 06, 2019 at 07:40:38PM -0300, Rodrigo Siqueira wrote:
> When vkms calls drm_universal_plane_init(), it sets 0 for the
> possible_crtcs parameter which works well for a single encoder and
> connector; however, this approach is not flexible and does not fit well
> for vkms. This commit adds an index parameter for vkms_plane_init()
> which makes code flexible and enables vkms to support other DRM features.
> 
> Signed-off-by: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>

I think a core patch to WARN_ON if this is NULL would be good. Since
that's indeed a bit broken ... We'd need to check all callers to make sure
there's not other such bugs anywhere ofc.
-Daniel

> ---
>  drivers/gpu/drm/vkms/vkms_drv.c    | 2 +-
>  drivers/gpu/drm/vkms/vkms_drv.h    | 4 ++--
>  drivers/gpu/drm/vkms/vkms_output.c | 6 +++---
>  drivers/gpu/drm/vkms/vkms_plane.c  | 4 ++--
>  4 files changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c
> index 738dd6206d85..92296bd8f623 100644
> --- a/drivers/gpu/drm/vkms/vkms_drv.c
> +++ b/drivers/gpu/drm/vkms/vkms_drv.c
> @@ -92,7 +92,7 @@ static int vkms_modeset_init(struct vkms_device *vkmsdev)
>  	dev->mode_config.max_height = YRES_MAX;
>  	dev->mode_config.preferred_depth = 24;
>  
> -	return vkms_output_init(vkmsdev);
> +	return vkms_output_init(vkmsdev, 0);
>  }
>  
>  static int __init vkms_init(void)
> diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
> index 81f1cfbeb936..e81073dea154 100644
> --- a/drivers/gpu/drm/vkms/vkms_drv.h
> +++ b/drivers/gpu/drm/vkms/vkms_drv.h
> @@ -113,10 +113,10 @@ bool vkms_get_vblank_timestamp(struct drm_device *dev, unsigned int pipe,
>  			       int *max_error, ktime_t *vblank_time,
>  			       bool in_vblank_irq);
>  
> -int vkms_output_init(struct vkms_device *vkmsdev);
> +int vkms_output_init(struct vkms_device *vkmsdev, int index);
>  
>  struct drm_plane *vkms_plane_init(struct vkms_device *vkmsdev,
> -				  enum drm_plane_type type);
> +				  enum drm_plane_type type, int index);
>  
>  /* Gem stuff */
>  struct drm_gem_object *vkms_gem_create(struct drm_device *dev,
> diff --git a/drivers/gpu/drm/vkms/vkms_output.c b/drivers/gpu/drm/vkms/vkms_output.c
> index 3b162b25312e..1442b447c707 100644
> --- a/drivers/gpu/drm/vkms/vkms_output.c
> +++ b/drivers/gpu/drm/vkms/vkms_output.c
> @@ -36,7 +36,7 @@ static const struct drm_connector_helper_funcs vkms_conn_helper_funcs = {
>  	.get_modes    = vkms_conn_get_modes,
>  };
>  
> -int vkms_output_init(struct vkms_device *vkmsdev)
> +int vkms_output_init(struct vkms_device *vkmsdev, int index)
>  {
>  	struct vkms_output *output = &vkmsdev->output;
>  	struct drm_device *dev = &vkmsdev->drm;
> @@ -46,12 +46,12 @@ int vkms_output_init(struct vkms_device *vkmsdev)
>  	struct drm_plane *primary, *cursor = NULL;
>  	int ret;
>  
> -	primary = vkms_plane_init(vkmsdev, DRM_PLANE_TYPE_PRIMARY);
> +	primary = vkms_plane_init(vkmsdev, DRM_PLANE_TYPE_PRIMARY, index);
>  	if (IS_ERR(primary))
>  		return PTR_ERR(primary);
>  
>  	if (enable_cursor) {
> -		cursor = vkms_plane_init(vkmsdev, DRM_PLANE_TYPE_CURSOR);
> +		cursor = vkms_plane_init(vkmsdev, DRM_PLANE_TYPE_CURSOR, index);
>  		if (IS_ERR(cursor)) {
>  			ret = PTR_ERR(cursor);
>  			goto err_cursor;
> diff --git a/drivers/gpu/drm/vkms/vkms_plane.c b/drivers/gpu/drm/vkms/vkms_plane.c
> index 0e67d2d42f0c..20ffc52f9194 100644
> --- a/drivers/gpu/drm/vkms/vkms_plane.c
> +++ b/drivers/gpu/drm/vkms/vkms_plane.c
> @@ -168,7 +168,7 @@ static const struct drm_plane_helper_funcs vkms_primary_helper_funcs = {
>  };
>  
>  struct drm_plane *vkms_plane_init(struct vkms_device *vkmsdev,
> -				  enum drm_plane_type type)
> +				  enum drm_plane_type type, int index)
>  {
>  	struct drm_device *dev = &vkmsdev->drm;
>  	const struct drm_plane_helper_funcs *funcs;
> @@ -190,7 +190,7 @@ struct drm_plane *vkms_plane_init(struct vkms_device *vkmsdev,
>  		funcs = &vkms_primary_helper_funcs;
>  	}
>  
> -	ret = drm_universal_plane_init(dev, plane, 0,
> +	ret = drm_universal_plane_init(dev, plane, 1 << index,
>  				       &vkms_plane_funcs,
>  				       formats, nformats,
>  				       NULL, type, NULL);
> -- 
> 2.21.0


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