Support `HDR_OUTPUT_METADATA` on more hardware

ThinkPad P1 Gen 3 (comet lake-h gt2) advertises HDR support but the HDR_OUTPUT_METADATA KMS property is not attached to the connector. @vsyrjala mentioned that in theory just attaching the property to the connector should work for this hardware.

added Community feature: display/Other labels

added platform: CML label

@suresh_kurmi @vsyrjala @jani.saarinen, Can you please confirm if HDR is supported on Comet lake ?

@uma_mnnit, are you aware ?

And why would not be?

Are there any logs we can see ? @swick can you add all relevant as instructed at: https://gitlab.freedesktop.org/drm/intel/-/wikis/How-to-file-i915-bugs

HDR_OUTPUT_METADATA affects only infoframe contents. Are the any reasons why one would not expose that property on all HDMI and DP connectors across all hardware in general?

The only concern is the size of the hardware buffer for the infoframe. It was increased on glk+. Someone needs to double check that the previous size was already big enough for the static HDR metadata.

mentioned in issue pq/color-and-hdr#9 (closed)

@vsyrjala Yeah the DRM (Dynamic Range and Mastering Infoframe) packet for HDR metadata (handled as DIP within Intel hardware)is not enabled for all platforms. It got enabled from Gen10 onwards i.e Geminilake/Icelake. This requires hardware support which is not there on all platforms.

It doesn't require anything except making sure the DIP buffer is big enough. Also someone did enable this for LSPCON already. So assuming the LPSCON case was actually confirmed to work/be correct then we should be able to just enable this pretty much across the board.

@vsyrjala I only got it enabled on lspcon on Gen9 devices, but that was through DP (DP to HDMI conversion done at pcon). On DP we do support on Gen9, it is sent as GMP packet (VDIP Enable GMP bit 4 in VIDEO_DIP_CTL). However for HDMI, this is supposed to be sent as DRM DIP packet (DRM_DIP_ENABLE bit 28 in VIDEO_DIP_CTL). These fields are not enabled for prior platforms or HDMI on Gen9. In absence of this, how we make sure that data is actually sent to sink or Am I missing something.

However we can attach this to DP connectors from Gen9+, this should be supported and work. Thoughts ?

Yeah, I was referring to DP specifically. I guess I forgot to mention that explicitly. It can probably be done for all hsw+ in fact (apart from the EDP transcoder) since I don't think the GMP DIP changed at all since then. HDMI might well be impossible for pre-glk.

Actually the GMP DIP does seem to be usable with HDMI as well. So HDMI might also be possible.

For HDMI, I guess even bandwidth will be a limiting factor. As HDR is mostly with 10bit and 4k, that is primarily why we had to use lspcon for gen9.

Nothing requires that you must use 4k video mode with HDR, so don't limit support based on that, please. E.g. my HDR display panel is much smaller than 4k.

If hardware cannot do at least 10-bit per channel pixels on any resolution, then that might be a reason to not bother exposing HDR features.

@pq Yeah, I have enabled it universally now wherever applicable. So we should be good here.

Thanks!

@vsyrjala Agree with you. I will sent out a patch extending the support for DP from hsw+. Thanks for the inputs.

https://patchwork.freedesktop.org/series/101708/ patch should fix it. Change is reviewed and merged to drm-intel-next. Thanks @vsyrjala for the review and valuable inputs.

mentioned in commit lyudess/linux@7e4e0e5c

Fixed by 7e4e0e5c3849 ("drm/i915/display: Extend DP HDR support to hsw+") in v5.19

closed