[Freedreno] [RFC] Expanding drm_mode_modeinfo flags

[Jeykumar Sankaran]

    Hello All, 
    	drm_mode_modeinfo::flags is a 32 bit field currently used to
    describe the properties of a connector mode. I see the least order 22 bits
    are already in use. Posting this RFC to discuss on any potential plans to 
    expand the bit range support of this field for growing mode properties and 
    ways to handle one such property needed by the msm dpu driver.

    msm drivers support panels which can dynamically switch between
    video(active) and command(smart) modes. Within video mode, they also support
    switching between resolutions seamlessly i.e. glitch free resolution switch.
    But they cannot do a seamless switch from a resolutions from video to
    command or vice versa. Clients need to be aware for these capablities before
    they switch between the resolutions. Since these capabilities are identified
    per drm_mode, we are considering the below two approaches to handle this
    use case.

    Option 1:
    Attached patch adds flag values to associate a drm_mode to video/command
    mode and to indicate its capability to do a seamless switch.

    Option 2:
    drm_mode_modeinfo can expose a new "private_flags" field to handle vendor
    specific mode flags. Besides the above mentioned use case, we are also
    expoloring methods to handle some of our display port resolution switch use
    cases where the DP ports can be operated in a tiled/detiled modes. This 
    approach will provide a standard channel for drm driver vendors for their 
    growing need for drm_mode specific capabilities.

    Please provide your inputs on the options or any upstream friendly
    recommendation to handle such custom use cases.

    Thanks and Regards,
    Jeykumar S.

Jeykumar Sankaran (1):
  drm: add mode flags in uapi for seamless mode switch

 include/uapi/drm/drm_mode.h | 5 +++++
 1 file changed, 5 insertions(+)

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