Re: [PATCH v11 06/11] drm: Add DRM client cap for aspect-ratio

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Fri, Apr 20, 2018 at 07:01:46PM +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
> 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
> 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.
> 
> 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: added comment explaining that no userspace breaks on aspect-ratio
>      mode bits.
> 
> Reviewed-by: Shashank Sharma <shashank.sharma@intel.com>
> ---
>  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..39c8eab 100644
> --- a/drivers/gpu/drm/drm_ioctl.c
> +++ b/drivers/gpu/drm/drm_ioctl.c
> @@ -325,6 +325,15 @@ drm_setclientcap(struct drm_device *dev, void *data, struct drm_file *file_priv)
>  		file_priv->atomic = req->value;
>  		file_priv->universal_planes = req->value;
>  		break;
> +	case DRM_CLIENT_CAP_ASPECT_RATIO:
> +		if (req->value > 1)
> +			return -EINVAL;
> +	/*
> +	 * No Atomic userspace blows up on aspect ratio mode bits. Checked in
> +	 * wayland/weston, xserver, and hardware-composer modeset paths.
> +	 */

Bogus indentation.

Also where's the aspect_ratio_allowed handling for the atomic cap?
Or did we decide against it after all?

> +		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

-- 
Ville Syrjälä
Intel
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