Re: [PATCH v2 12/17] drm/vc4: crtc: Introduce a lower-level crtc init helper

["Maíra Canal" <mcanal@igalia.com>]

On 11/28/22 11:53, Maxime Ripard wrote:
> The current vc4_crtc_init() helper assumes that we will be using
> hardware planes and calls vc4_plane_init().
> 
> While it's a reasonable assumption, we'll want to mock the plane and
> thus provide our own. Let's create a helper that will take the plane as
> an argument.
> 
> Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
> Signed-off-by: Maxime Ripard <maxime@cerno.tech>

Although the commit message explains a bit about why __vc4_crtc_init is
being created, it would be nice to add a comment in the code explaining
that __vc4_crtc_init can be used for tests as it allows mocking the
plane. This way the distinction between vc4_crtc_init and
__vc4_crtc_init will be cleaner to the reader.

Reviewed-by: Maíra Canal <mcanal@igalia.com>

Best Regards,
- Maíra Canal

> ---
>  drivers/gpu/drm/vc4/vc4_crtc.c | 52 +++++++++++++++++++++++++++---------------
>  drivers/gpu/drm/vc4/vc4_drv.h  |  6 +++++
>  2 files changed, 39 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vc4/vc4_crtc.c b/drivers/gpu/drm/vc4/vc4_crtc.c
> index 333529ed3a0d..7a2c54efecb0 100644
> --- a/drivers/gpu/drm/vc4/vc4_crtc.c
> +++ b/drivers/gpu/drm/vc4/vc4_crtc.c
> @@ -1286,31 +1286,20 @@ static void vc4_set_crtc_possible_masks(struct drm_device *drm,
>  	}
>  }
>  
> -int vc4_crtc_init(struct drm_device *drm, struct platform_device *pdev,
> -		  struct vc4_crtc *vc4_crtc,
> -		  const struct vc4_crtc_data *data,
> -		  const struct drm_crtc_funcs *crtc_funcs,
> -		  const struct drm_crtc_helper_funcs *crtc_helper_funcs,
> -		  bool feeds_txp)
> +int __vc4_crtc_init(struct drm_device *drm,
> +		    struct platform_device *pdev,
> +		    struct vc4_crtc *vc4_crtc,
> +		    const struct vc4_crtc_data *data,
> +		    struct drm_plane *primary_plane,
> +		    const struct drm_crtc_funcs *crtc_funcs,
> +		    const struct drm_crtc_helper_funcs *crtc_helper_funcs,
> +		    bool feeds_txp)
>  {
>  	struct vc4_dev *vc4 = to_vc4_dev(drm);
>  	struct drm_crtc *crtc = &vc4_crtc->base;
> -	struct drm_plane *primary_plane;
>  	unsigned int i;
>  	int ret;
>  
> -	/* For now, we create just the primary and the legacy cursor
> -	 * planes.  We should be able to stack more planes on easily,
> -	 * but to do that we would need to compute the bandwidth
> -	 * requirement of the plane configuration, and reject ones
> -	 * that will take too much.
> -	 */
> -	primary_plane = vc4_plane_init(drm, DRM_PLANE_TYPE_PRIMARY, 0);
> -	if (IS_ERR(primary_plane)) {
> -		dev_err(drm->dev, "failed to construct primary plane\n");
> -		return PTR_ERR(primary_plane);
> -	}
> -
>  	vc4_crtc->data = data;
>  	vc4_crtc->pdev = pdev;
>  	vc4_crtc->feeds_txp = feeds_txp;
> @@ -1342,6 +1331,31 @@ int vc4_crtc_init(struct drm_device *drm, struct platform_device *pdev,
>  	return 0;
>  }
>  
> +int vc4_crtc_init(struct drm_device *drm, struct platform_device *pdev,
> +		  struct vc4_crtc *vc4_crtc,
> +		  const struct vc4_crtc_data *data,
> +		  const struct drm_crtc_funcs *crtc_funcs,
> +		  const struct drm_crtc_helper_funcs *crtc_helper_funcs,
> +		  bool feeds_txp)
> +{
> +	struct drm_plane *primary_plane;
> +
> +	/* For now, we create just the primary and the legacy cursor
> +	 * planes.  We should be able to stack more planes on easily,
> +	 * but to do that we would need to compute the bandwidth
> +	 * requirement of the plane configuration, and reject ones
> +	 * that will take too much.
> +	 */
> +	primary_plane = vc4_plane_init(drm, DRM_PLANE_TYPE_PRIMARY, 0);
> +	if (IS_ERR(primary_plane)) {
> +		dev_err(drm->dev, "failed to construct primary plane\n");
> +		return PTR_ERR(primary_plane);
> +	}
> +
> +	return __vc4_crtc_init(drm, pdev, vc4_crtc, data, primary_plane,
> +			       crtc_funcs, crtc_helper_funcs, feeds_txp);
> +}
> +
>  static int vc4_crtc_bind(struct device *dev, struct device *master, void *data)
>  {
>  	struct platform_device *pdev = to_platform_device(dev);
> diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h
> index 051c2e3b6d43..cd2002fff115 100644
> --- a/drivers/gpu/drm/vc4/vc4_drv.h
> +++ b/drivers/gpu/drm/vc4/vc4_drv.h
> @@ -888,6 +888,12 @@ int vc4_bo_debugfs_init(struct drm_minor *minor);
>  /* vc4_crtc.c */
>  extern struct platform_driver vc4_crtc_driver;
>  int vc4_crtc_disable_at_boot(struct drm_crtc *crtc);
> +int __vc4_crtc_init(struct drm_device *drm, struct platform_device *pdev,
> +		    struct vc4_crtc *vc4_crtc, const struct vc4_crtc_data *data,
> +		    struct drm_plane *primary_plane,
> +		    const struct drm_crtc_funcs *crtc_funcs,
> +		    const struct drm_crtc_helper_funcs *crtc_helper_funcs,
> +		    bool feeds_txp);
>  int vc4_crtc_init(struct drm_device *drm, struct platform_device *pdev,
>  		  struct vc4_crtc *vc4_crtc, const struct vc4_crtc_data *data,
>  		  const struct drm_crtc_funcs *crtc_funcs,
>