Hi, CPU: Skylake Core I series, (i3-6100) SW Environment: (from 01.org, 2016Q2) Based on Ubuntu 16.04, and change the Kernel and libraries: Linux kernel: 4.6 Mesa - 11.2.2 xf86-video-intel - 2.99.917 Libdrm - 2.4.68 Libva - 1.7.1 vaapi intel-driver - 1.7.1 Cairo - 1.15.2 Xorg Xserver - 1.18.3 If we connect the HDMI 2.0 port between our produce and most monitors (support 4K@60), the monitor shows the resolution 4K@60 normally. But if we connect the HDMI 2.0 port between our produce and most TVs (support 4K@60), the TV just shows the resolution 4K@30. "xrandr" command doesn't show 4K@60. We also found some TVs just support 4:2:0 YCbCr. Has Linux driver not support it yet?
Updating to SKL rather than APL based on the details you have provided. Please change if this is not correct and update also your information.
Looking at i3-6100 Graphics Specifications (Intel® HD Graphics 520 or 530) from http://ark.intel.com/compare/90734,89063,88180,90611,88181 : Max Resolution (HDMI 1.4): 4096x2304@24Hz What is your motherboard model? Execute command: sudo dmidecode -t 2 I think YCbCr is Platform-Common, so it should be supported. What is the TV model and could you attach some logs (dmesg from fresh boot and xrandr output)?
(In reply to Jun Zhao from comment #0) > We also found some TVs just support 4:2:0 YCbCr. Has Linux driver not > support it yet? No support as of now.
(In reply to Ville Syrjala from comment #3) > (In reply to Jun Zhao from comment #0) > > We also found some TVs just support 4:2:0 YCbCr. Has Linux driver not > > support it yet? > > No support as of now. Just to elaborat ea bit. For SKL and whatnot the only way to get it would be via an external DP->HDMI 2.0 dongle/cable, or via LSPCON (which is the same thing pretty much). Adding the support would involve several parts: 1) Add all the generic HDMI forum VSDB parsing and whatnot to the EDID parser This is needed so that we'll know whether the sink supports YCbCr 4:2:0. There have been some patches towards HDMI 2.0 support for the EDID parser, but I can't recall how much was still missing from them. Not much merged so far. 3) Implement YCbCr 4:4:4 output support This would involve doing RGB->YCbCr conversion with the pipe CSC. I started to implement this at some point, but got sidetracked and never actually finished. I should probably have a branch with some half finished code somewhere. 2) Extend out DP->HDMI dongle support to allow YCbCr 4:2:0 output. Looking at the DP 1.4 spec, I see a PROTOCOL_CONVERTER_CONTROL_1 register that would allow you to enable YCbCr 4:2:0 conversion. If I'm reading things correctly we need to output YCbCr 4:4:4 to the dongle, and then dongle will downsample that to 4:2:0 when instructed to do so via this register. We probably have to parse a few other things from the DPCD as well so that we'll know whether the dongle even supports this.
We use Megachip MDCP2800 in this case. It works fine with Windows system on the same board.
(In reply to JingWu Lin from comment #5) > We use Megachip MDCP2800 in this case. > It works fine with Windows system on the same board. Sounds somewhat similar to: https://bugs.freedesktop.org/show_bug.cgi?id=94248 Have you already checked and updated the firmware of your MegaChips MCDP2800 LSPCon? And are you running the latest Kernel and so on?
JingWu Lin - please note the question on comment 6. And does the problem still persist with latest kernel (preferable drm-tip from git://anongit.freedesktop.org/git/drm-tip) ?
Closing this bug as invalid because the lack of response please if the problem is visible test with latest configuration and open a new bug, include logs.
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