Re: [Intel-gfx] [PATCH v13 07/10] drm: Handle aspect ratio info in legacy modeset path

[Daniel Vetter <daniel@ffwll.ch>]

On Wed, May 02, 2018 at 12:20:19PM +0530, Nautiyal, Ankit K wrote:
> From: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
> 
> If the user-space does not support aspect-ratio, and requests for a
> modeset with mode having aspect ratio bits set, then the given
> user-mode must be rejected. Secondly, while preparing a user-mode from
> kernel mode, the aspect-ratio info must not be given, if aspect-ratio
> is not supported by the user.
> 
> This patch:
> 1. rejects the modes with aspect-ratio info, during modeset, if the
>    user does not support aspect ratio.
> 2. does not load the aspect-ratio info in user-mode structure, if
>    aspect ratio is not supported.
> 3. adds helper functions for determining if aspect-ratio is expected
>    in user-mode and for allowing/disallowing the aspect-ratio, if its
>    not expected.
> 
> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
> 
> V3: Addressed review comments from Ville:
>     Do not corrupt the current crtc state by updating aspect-ratio on
>     the fly.
> V4: rebase
> V5: As suggested by Ville, rejected the modeset calls for modes with
>     aspect ratio, if the user does not set aspect-ratio cap.
> V6: Used the helper functions for determining if aspect-ratio is
>     expected in the user-mode.
> V7: rebase
> V8: rebase
> V9: rebase
> V10: Modified the commit-message
> V11: rebase
> V12: Merged the patch for adding aspect-ratio helper functions
>      with this patch.
> V13: Minor modifications as suggested by Ville.
> ---
>  drivers/gpu/drm/drm_crtc.c          |  8 +++++++
>  drivers/gpu/drm/drm_crtc_internal.h |  6 +++++
>  drivers/gpu/drm/drm_modes.c         | 47 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 61 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> index a231dd5..98323f4 100644
> --- a/drivers/gpu/drm/drm_crtc.c
> +++ b/drivers/gpu/drm/drm_crtc.c
> @@ -449,6 +449,7 @@ int drm_mode_getcrtc(struct drm_device *dev,
>  			crtc_resp->mode_valid = 0;
>  		}
>  	}
> +	drm_mode_filter_aspect_ratio_flags(file_priv, &crtc_resp->mode);
>  	drm_modeset_unlock(&crtc->mutex);
>  
>  	return 0;
> @@ -628,6 +629,13 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data,
>  			ret = -ENOMEM;
>  			goto out;
>  		}
> +		if (!drm_mode_aspect_ratio_allowed(file_priv,
> +						   &crtc_req->mode)) {
> +			DRM_DEBUG_KMS("Unexpected aspect-ratio flag bits\n");
> +			ret = -EINVAL;
> +			goto out;
> +		}
> +
>  
>  		ret = drm_mode_convert_umode(dev, mode, &crtc_req->mode);
>  		if (ret) {
> diff --git a/drivers/gpu/drm/drm_crtc_internal.h b/drivers/gpu/drm/drm_crtc_internal.h
> index 5d307b2..31d6c77 100644
> --- a/drivers/gpu/drm/drm_crtc_internal.h
> +++ b/drivers/gpu/drm/drm_crtc_internal.h
> @@ -222,3 +222,9 @@ int drm_mode_page_flip_ioctl(struct drm_device *dev,
>  void drm_mode_fixup_1366x768(struct drm_display_mode *mode);
>  void drm_reset_display_info(struct drm_connector *connector);
>  u32 drm_add_display_info(struct drm_connector *connector, const struct edid *edid);
> +
> +/* drm_modes.c */
> +bool drm_mode_aspect_ratio_allowed(const struct drm_file *file_priv,
> +				   struct drm_mode_modeinfo *umode);
> +void drm_mode_filter_aspect_ratio_flags(const struct drm_file *file_priv,
> +					struct drm_mode_modeinfo *umode);
> diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
> index c395a24..2bf2f0b 100644
> --- a/drivers/gpu/drm/drm_modes.c
> +++ b/drivers/gpu/drm/drm_modes.c
> @@ -1759,3 +1759,50 @@ bool drm_mode_is_420(const struct drm_display_info *display,
>  		drm_mode_is_420_also(display, mode);
>  }
>  EXPORT_SYMBOL(drm_mode_is_420);
> +
> +/**
> + * drm_mode_aspect_ratio_allowed - checks if the aspect-ratio information
> + * is expected from the user-mode.
> + *
> + * If the user has set aspect-ratio cap, then the flag of the user-mode is
> + * allowed to contain aspect-ratio value.
> + * If the user does not set aspect-ratio cap, then the only value allowed in the
> + * flags bits is aspect-ratio NONE.
> + *
> + * @file_priv: file private structure to get the user capabilities
> + * @umode: drm_mode_modeinfo struct, whose flag carry the aspect ratio
> + * information.
> + *
> + * Returns:
> + * true if the aspect-ratio info is allowed in the user-mode flags.
> + * false, otherwise.
> + */

We generally don't do full kerneldoc for drm.ko internal functions (which
these both are), only for driver functions. I'd remove them both because
they don't add a hole lot really.

> +bool
> +drm_mode_aspect_ratio_allowed(const struct drm_file *file_priv,
> +			      struct drm_mode_modeinfo *umode)

I don't really see the point of this helper. It has a bit a confusing
name, and open-code it looks simpler to me in setcrtc.

> +{
> +	if (file_priv->aspect_ratio_allowed ||
> +	    (umode->flags & DRM_MODE_FLAG_PIC_AR_MASK) == DRM_MODE_FLAG_PIC_AR_NONE)
> +		return true;
> +	return false;
> +}
> +
> +/**
> + * drm_mode_filter_aspect_ratio_flags - filters the aspect-ratio bits in the
> + * user-mode flags.
> + *
> + * Checks if the aspect-ratio information is allowed. Resets the aspect-ratio
> + * bits in the user-mode flags, if aspect-ratio info is not allowed.
> + *
> + * @file_priv: file private structure to get the user capabilities.
> + * @umode: drm_mode_modeinfo struct, whose flags' aspect-ratio bits needs to
> + * be filtered.
> + *
> + */
> +void
> +drm_mode_filter_aspect_ratio_flags(const struct drm_file *file_priv,
> +				   struct drm_mode_modeinfo *umode)
> +{
> +	if (!drm_mode_aspect_ratio_allowed(file_priv, umode))

You only need to check for file_priv->aspect_ratio_allowed here, then
clear unconditionally.
-Daniel

> +		umode->flags &= ~DRM_MODE_FLAG_PIC_AR_MASK;
> +}
> -- 
> 2.7.4
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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