Re: [Intel-gfx] [PATCH v13 06/10] drm: Add DRM client cap for aspect-ratio

[Daniel Vetter <daniel@ffwll.ch>]

On Wed, May 02, 2018 at 12:20:18PM +0530, Nautiyal, Ankit K wrote:
> From: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
> 
> To enable aspect-ratio support in DRM, blindly exposing the aspect
> ratio information along with mode, can break things in existing
> non-atomic user-spaces which have no intention or support to use this
> aspect ratio information.
> 
> To avoid this, a new drm client cap is required to enable a non-atomic
> user-space to advertise if it supports modes with aspect-ratio. Based
> on this cap value, the kernel will take a call on exposing the aspect
> ratio info in modes or not.
> 
> This patch adds the client cap for aspect-ratio.
> 
> Since no atomic-userspaces blow up on receiving aspect-ratio
> information, the client cap for aspect-ratio is always enabled
> for atomic clients.
> 
> Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
> Cc: Shashank Sharma <shashank.sharma@intel.com>
> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
> 
> V3: rebase
> V4: As suggested by Marteen Lankhorst modified the commit message
>     explaining the need to use the DRM cap for aspect-ratio. Also,
>     tweaked the comment lines in the code for better understanding and
>     clarity, as recommended by Shashank Sharma.
> V5: rebase
> V6: rebase
> V7: rebase
> V8: rebase
> V9: rebase
> V10: rebase
> V11: rebase
> V12: As suggested by Daniel Vetter and Ville Syrjala,
>      always enable aspect-ratio client cap for atomic userspaces,
>      if no atomic userspace breaks on aspect-ratio bits.
> V13: rebase
> 
> Reviewed-by: Shashank Sharma <shashank.sharma@intel.com>

Yeah this is what I had in mind with auto-enabling this for atomic
clients.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

> ---
>  drivers/gpu/drm/drm_ioctl.c | 9 +++++++++
>  include/drm/drm_file.h      | 8 ++++++++
>  include/uapi/drm/drm.h      | 7 +++++++
>  3 files changed, 24 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
> index af78291..0379983 100644
> --- a/drivers/gpu/drm/drm_ioctl.c
> +++ b/drivers/gpu/drm/drm_ioctl.c
> @@ -324,6 +324,15 @@ drm_setclientcap(struct drm_device *dev, void *data, struct drm_file *file_priv)
>  			return -EINVAL;
>  		file_priv->atomic = req->value;
>  		file_priv->universal_planes = req->value;
> +		/*
> +		 * No atomic user-space blows up on aspect ratio mode bits.
> +		 */
> +		file_priv->aspect_ratio_allowed = req->value;
> +		break;
> +	case DRM_CLIENT_CAP_ASPECT_RATIO:
> +		if (req->value > 1)
> +			return -EINVAL;
> +		file_priv->aspect_ratio_allowed = req->value;
>  		break;
>  	default:
>  		return -EINVAL;
> diff --git a/include/drm/drm_file.h b/include/drm/drm_file.h
> index 5176c37..02b7dde 100644
> --- a/include/drm/drm_file.h
> +++ b/include/drm/drm_file.h
> @@ -182,6 +182,14 @@ struct drm_file {
>  	unsigned atomic:1;
>  
>  	/**
> +	 * @aspect_ratio_allowed:
> +	 *
> +	 * True, if client can handle picture aspect ratios, and has requested
> +	 * to pass this information along with the mode.
> +	 */
> +	unsigned aspect_ratio_allowed:1;
> +
> +	/**
>  	 * @is_master:
>  	 *
>  	 * This client is the creator of @master. Protected by struct
> diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
> index 6fdff59..9c660e1 100644
> --- a/include/uapi/drm/drm.h
> +++ b/include/uapi/drm/drm.h
> @@ -680,6 +680,13 @@ struct drm_get_cap {
>   */
>  #define DRM_CLIENT_CAP_ATOMIC	3
>  
> +/**
> + * DRM_CLIENT_CAP_ASPECT_RATIO
> + *
> + * If set to 1, the DRM core will provide aspect ratio information in modes.
> + */
> +#define DRM_CLIENT_CAP_ASPECT_RATIO    4
> +
>  /** DRM_IOCTL_SET_CLIENT_CAP ioctl argument type */
>  struct drm_set_client_cap {
>  	__u64 capability;
> -- 
> 2.7.4
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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