On Tue, 24 May 2022 14:33:20 -0400 Harry Wentland harry.wentland@amd.com wrote:

The supported EOTFs are defined in eotf_supported in drm_edid but userspace has no way of knowing what is and isn't supported when creating an HDR_OUTPUT_METADATA and will only know something is wrong when the atomic commit fails.

Hi Harry,

maybe clarify here the two different sets of "supported": EDID data vs. kernel code? I think the paragraph uses the same word for both meanings.

Since it is expected that userspace reads the EDID to understand what the display supports it doesn't make sense for DRM to block an HDR_OUTPUT_METADATA if it contains an EOTF the kernel doesn't understand.

This comes with the added benefit of future-proofing metadata support. If the spec defines a new EOTF there is no need to update DRM and an compositor can immediately make use of it.

Fixes: https://gitlab.freedesktop.org/wayland/weston/-/issues/609

Signed-off-by: Harry Wentland harry.wentland@amd.com Cc: ppaalanen@gmail.com Cc: sebastian.wick@redhat.com Cc: vprosyak@amd.com Cc: Uma Shankar uma.shankar@intel.com

Acked-by: Pekka Paalanen pekka.paalanen@collabora.com

Thanks, pq

---

drivers/gpu/drm/drm_edid.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c index 12893e7be89b..223f96a72064 100644 --- a/drivers/gpu/drm/drm_edid.c +++ b/drivers/gpu/drm/drm_edid.c @@ -5691,10 +5691,8 @@ drm_hdmi_infoframe_set_hdr_metadata(struct hdmi_drm_infoframe *frame,

/* Sink EOTF is Bit map while infoframe is absolute values */ if (!is_eotf_supported(hdr_metadata->hdmi_metadata_type1.eotf,

•    connector->hdr_sink_metadata.hdmi_type1.eotf)) {
  

• DRM_DEBUG_KMS("EOTF Not Supported\n");
  

• return -EINVAL;
  

• }

•    connector->hdr_sink_metadata.hdmi_type1.eotf))
  

• DRM_DEBUG_KMS("Unknown EOTF %d\n", hdr_metadata->hdmi_metadata_type1.eotf);
  
  

  err = hdmi_drm_infoframe_init(frame); if (err < 0)