video/hdmi: Add Unpack only function for DRM infoframe

It adds an unpack only function for DRM infoframe for dynamic range and
mastering infoframe readout.
It unpacks the information data block contained in the binary buffer into
a structured frame of the HDMI Dynamic Range and Mastering (DRM)
information frame.

In contrast to hdmi_drm_infoframe_unpack() function, it does not verify
a checksum.

It can be used for unpacking a DP HDR Metadata Infoframe SDP case.
DP HDR Metadata Infoframe SDP uses the same Dynamic Range and Mastering
(DRM) information (CTA-861-G spec.) such as HDMI DRM infoframe.
But DP SDP header and payload structure are different from HDMI DRM
Infoframe. Therefore unpacking DRM infoframe for DP requires skipping of
a verifying checksum.

v9: Add clear comments to hdmi_drm_infoframe_unpack_only() and
    hdmi_drm_infoframe_unpack() (Laurent Pinchart)

Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200514060732.3378396-2-gwan-gyeong.mun@intel.com

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/hdmi.h b/include/linux/hdmi.h
index 9613d796cfb1..50c31f1a0a2d 100644
--- a/include/linux/hdmi.h
+++ b/include/linux/hdmi.h
@@ -219,6 +219,8 @@ ssize_t hdmi_drm_infoframe_pack(struct hdmi_drm_infoframe *frame, void *buffer,
 ssize_t hdmi_drm_infoframe_pack_only(const struct hdmi_drm_infoframe *frame,
 				     void *buffer, size_t size);
 int hdmi_drm_infoframe_check(struct hdmi_drm_infoframe *frame);
+int hdmi_drm_infoframe_unpack_only(struct hdmi_drm_infoframe *frame,
+				   const void *buffer, size_t size);
 
 enum hdmi_spd_sdi {
 	HDMI_SPD_SDI_UNKNOWN,