I have two monitors plugged into DisplayPort connectors on my Radeon HD7970, and a further HDMI connection to my amp and TV. As of upgrading to kernel 4.0.0, the third display briefly (for ~1s or so) shows a desktop backdrop when the system is first booted, then reverts to just showing white snow. All full-screen hardware decoding (via vdpau / vaa) operations are broken, resulting in "radeon: The kernel rejected CS" type messages on the terminal. Inspection of dmesg shows messages like: May 3 19:26:40 gentoo kernel: [drm:radeon_uvd_cs_parse [radeon]] *ERROR* Failed mapping the UVD message (-22)! May 3 19:26:40 gentoo kernel: [drm:radeon_cs_ioctl [radeon]] *ERROR* Invalid command stream ! These effects are 100% reproducible on my system. Rolling back to an older kernel fixes the problem (3.18.9 works fine, I haven't binary chopped all versions in between yet). Reproducible: Always Steps to Reproduce: 1. Boot to X with TV (3rd display) powered on & connected to HDMI 2. 3. Actual Results: White noise / snow only shown on 3rd display. Expected Results: Extended desktop on 3rd display.
is this still a problem with more recent kernel ? Please open a new bug if the problem persist with a more recent kernel
