<html> <head> <base href="https://bugs.freedesktop.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW - [SKL] Can we support YCbCr 420 output in HDMI 2.0 port?" href="https://bugs.freedesktop.org/show_bug.cgi?id=97774#c4">Comment # 4</a> on <a class="bz_bug_link bz_status_NEW " title="NEW - [SKL] Can we support YCbCr 420 output in HDMI 2.0 port?" href="https://bugs.freedesktop.org/show_bug.cgi?id=97774">bug 97774</a> from <a class="email" href="mailto:ville.syrjala@linux.intel.com" title="Ville Syrjala <ville.syrjala@linux.intel.com>"> Ville Syrjala</a> <pre>(In reply to Ville Syrjala from <a href="show_bug.cgi?id=97774#c3">comment #3</a>) > (In reply to Jun Zhao from <a href="show_bug.cgi?id=97774#c0">comment #0</a>) > > 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.</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the assignee for the bug.</li> <li>You are on the CC list for the bug.</li> <li>You are the QA Contact for the bug.</li> </ul> </body> </html>