DRM Client capability for aspect ratio

"Nautiyal, Ankit K" <ankit.k.nautiyal@xxxxxxxxx> · Tue, 17 Oct 2017 15:38:14 +0530



    Hi All,
    
      
    I am working
          for adding the DRM Client cap for
          the aspect ratio support as part of the series: 
    
    
    https://patchwork.freedesktop.org/series/10850/
          : Picture
            aspect ratio support in DRM layer by Shashank Sharma.
    
    
    I have an
          open as to how to go about it.
    
    
    I was going
          through the existing DRM Client Cap
          like DRM_CLIENT_CAP_STEREO_3D, DRM_CLIENT_CAP_ATOMIC.
    
    
    On Similar
          lines, I was able to add the new DRM_CLIENT_CAP_ASPECT_RATIO.
          I also added a member 'aspect_ratio_required' in drm_file
          structure,
    
    
    which is
          set, when the client calls
          drm_setclientcap( ), for aspect ratio, just like its being
          done for other DRM
          Client Caps. 
    
    
    Now what I
          want to do is 
    
    
    1.     Setting the
          aspect-ratio flag-bits (19-22) in drmModeModeInfo only if
          the client
          advertises that it requires the aspect-ratio.
    
    
    So I need to have
          this information (that client requires aspect ratio) available
          in the function:
    
    
    drm_mode_convert_to_umode(
            )
          : Where the flag bits are actually set
    
    
    2.     Similarly in case of
          modeset request from the client, we would want to parse the
          aspect ratio bits
          from the requested  drmModeModeInfo
          only
          if the client requires aspect ratio. 
    
    
    This
          will require change in the function:
    
    
    drm_mode_convert_umode()  : Where
          the flag bits of  drm_mode_mode_info are read by the drm layer
          to
          determine the aspect ratio and set in drm_display_mode)
    
    
    The problem
          is that, both these functions have
          drm_mode_mode_info and drm_display_mode as the only arguments,
          but our flag
          aspect_ratio_required is in file_priv (struct drm_file).
    
    
    To do this
          there are two ways I can think of:
    
    
    1.     Change the
        drm_mode_convert_umode() to include aspect_ratio_required flag.

      
            Before calling this function, the
        file_priv->aspect_ratio_required will be
        checked and the flag will be set accordingly.
      
    2.    
        While getting
        the drmClientCap from client, instead of storing this
        information in file-priv,
        store this info in some other structure.
    
    
    Is
        my
        understanding correct or is there any other way I should handle
        the drm client
        cap?
    
    
    Thanks
        and
        Regards,
    
    
    Ankit

      
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