Hi, I finally got some time to investigate further.
Setup I'm running Debian Stretch with a backported 4.13 Linux kernel on an Intel Kaby Lake (chipset H110 and HD graphics 630) machine. I've installed firmware-misc-nonfree and updated my BIOS to fix the Kavy Lake HT bug. Problem I'm experiencing red blinking pixels in dark areas in the displayed Xorg picture on my TV connected using a HDMI cable. Looking more closely, I also see blue pixels. Those anomalies seem to follow colors in the displayed picture. They occur on the root window, in mpv, vlc, at least, it seems color based and not app based. Hardware tests Two other PCs (Linux and Windows) going through the same HDMI cable to the same TV and same TV port using the same 1920x1080 resolution work perfectly. The same PC when using Windows 10 also displays a perfect picture. Using a HDMI port multiplier makes the problem worse. Outputting to another 1920x1080 monitor works well. Software tests Ubuntu 17.10 on a live CD show the same symptoms. I've tried multiple combinations of Xorg setup with no working setup : - modesetting Xorg driver with glamor or none as AccelMethod - intel Xorg driver with sna or uxa as AccelMethod, DRI 2 or 3. I've also tried with i915.enable_rc6=0 and this does not change anything. Lowering the resolution to 1280x720 works around the problem. My conclusion Windows 10 manage to setup the video GPU to input a stronger HDMI signal and my TV is sensitive to this. I was wondering if there was anything I could investigate further regarding this. I would also love to get any other idea or pointer regarding solving this. Thanks for reading, Alex
