[Bug 110496] [GLK] no signal - with samsung 4k TV - HDMI UHD Color (ENABLED)

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=110496

--- Comment #29 from sergey79 at gmail.com ---
(In reply to shashank.sharma at intel.com from comment #27)

> That's why we can see 4k at 30 deep color, 4k at 60 YCBCR 420 deep color outputs
> working on this TV, but as soon as we switch to RGB 4k at 60, the driver
> restricts the HDMI output to 4k at 60 8BPC, which is being rejected by the TV,
> in the UHD mode of operation.

420 works only @50/60Hz, only @ 8-bit. 420 @ deep color and other refresh rates
(24/25/30) is not supported by the TV at all (with UHD Color on or off).

The only difference between "HDMI UHD Color" on and off is that TV sends
different EDID data. I analyzed both EDIDs - basically the only important
difference is the presence of HDMI-Forum VSDB block which enable Deep Color in
4k modes. 

4k modes that work (UHD Color off):
RGB 24/25/30Hz 8-bit
420 50/60Hz 8-bit

4k modes that don't work (UHD Color on):
RGB 24/25/30Hz 12-bit
RGB 50/60Hz 8-bit

As you can see, any mode that require 594 Mhz pixel clock - does not work. And
any mode that require only 297 Mhz - works just fine.

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