Running linus master of today (also reproduced on 3.13), with this hardware: 00:02.0 VGA compatible controller [0300]: Intel Corporation ValleyView Gen7 [8086:0f31] (rev 0e) Inside a Bay Trail M N2807 Choosing any of the 3 interlaced resolutions supported by my display results in a "wobbly" output. It is as if on every update, even for static images, each horizontal row of pixels gets jolted up/down/up/down. I captured a video, the camera compensated a lot, it feels a lot worse than it looks here, but to give you an idea: https://www.youtube.com/watch?v=C9QhNf8fGxI Please let me know how I can help with diagnosis/debug.
For starters, please attach dmesg with drm.debug=14 module parameter set, all the way from boot to when you see the problem, so we get a bit more info about your system.
Created attachment 115060 [details] dmesg dmesg with drm.debug=14 and a video parameter to select 1080i during boot, the display is bad from the first moment that something appears on-screen.
Shot in the dark, can you try choosing this mode with xrandr (I don't think you can specify it on the kernel cmdline): Modeline 65:"1920x1080i" 60 74176 1920 2008 2052 2200 1080 1084 1094 1125 0x40 0x15 It has a slightly different clock.
That looks to be a very standard cea 1080i mode, and those are working just fine on my BYT here with a Samsung TV. So I'm thinking this could a be a problem with the display itself. Have you tried plugging this display into some other machine with another graphics card?
You're right, it does seem to work OK against an actual TV. Really strange because I tested against 2 PC screens, one from Dell and one from LG, both offer 1080i in the EDID and suggest that 1080i is supported in the spec sheet; they say "1080i" in the OSD when that mode is selected, but wobble horribly. I also tested both displays against a laptop with AMD graphics, both under Linux and Windows. In all cases the wobble is there too. So as strange as it is, this would appear to be a problem with the displays themselves.
(In reply to Daniel Drake from comment #5) > So as strange as it is, this would appear to be a problem with the displays > themselves. Closing as INVALID.
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