<html> <head> <base href="https://bugs.freedesktop.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_ASSIGNED " title="ASSIGNED - [GLK] no signal - with samsung 4k TV - HDMI UHD Color (ENABLED)" href="https://bugs.freedesktop.org/show_bug.cgi?id=110496#c27">Comment # 27</a> on <a class="bz_bug_link bz_status_ASSIGNED " title="ASSIGNED - [GLK] no signal - with samsung 4k TV - HDMI UHD Color (ENABLED)" href="https://bugs.freedesktop.org/show_bug.cgi?id=110496">bug 110496</a> from <a class="email" href="mailto:shashank.sharma@intel.com" title="shashank.sharma@intel.com <shashank.sharma@intel.com>"> shashank.sharma@intel.com</a> <pre>As I had mentioned previously, I dont have access to this monitor, but based on the observations shared by everyone, this is what I think is happening: - HDMI 2.0 spec can support a max clock of 600Mhz. - Samsung TVs with UHD mode of display expect > 8BPC from the source in this mode of operations. This means you have to at-least drive 10 BPC output from SOC display. - 4K@60 modes (RGB/YCBCR444) need 597Mhz clock in 8 BPC mode of operation and will need > 597 Mhz clock to drive 4k@60 10/12/16 BPC. - 4K@30 modes (RGB/YCBCR444) need 297Mhz clock for 8 BPC mode of operation, so it can even go up-to 16 BPC, which will still be with-in the 600Mhz range. - YCBCR 4:2:0 needs half the clock, than RGB/YCBCR444 mode of operation. This means 4K@60 YCBCR420 output will need a clock of 597 Mhz and which further means we can drive 4k@60 10/12/16 BPC with YCBCR420 output, with-in the 600 Mhz clock range. That's why we can see 4k@30 deep color, 4k@60 YCBCR 420 deep color outputs working on this TV, but as soon as we switch to RGB 4k@60, the driver restricts the HDMI output to 4k@60 8BPC, which is being rejected by the TV, in the UHD mode of operation. - Shashank</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are on the CC list for the bug.</li> <li>You are the QA Contact for the bug.</li> </ul> </body> </html>