Hey If I switch from Xorg to fbcon, I get an unwanted "animation". It takes exactly 4 frames until the new fbcon content is properly displayed. Each frame moves the content by 25% from the right (and sometimes left) side into the screen. It really looks like an intended animation that "moves" in the new screen from the right side. This only happens if I use the intel DDX with SNA enabled. I neither happens with UXA nor modesetting+glamour. In fact, I can only reproduce it with SNA. I've been experiencing this for quite a while (~1 year?), but it looked really intentional, so I wasn't aware this is not a feature. Until today, as I tried asking how to disable it and no-one knew what I was talking about.. I don't mind much, I mean it really looks rather nice. But maybe you guys care. It's an HSW machine (Lenovo X240), and the only noticeable log message is this: Jun 18 20:12:15 david-t2 kernel: [drm:intel_set_cpu_fifo_underrun_reporting [i915]] *ERROR* uncleared fifo underrun on pipe A Jun 18 20:12:15 david-t2 kernel: [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun (which happens exactly once at boot). I can run this with drm.debug=foobar if you want. Just let me know what kind of information you need. Thanks! gen: 7 pch: 3 is_mobile: yes is_i85x: no is_i915g: no is_i945gm: no is_g33: no need_gfx_hws: yes is_g4x: no is_pineview: no is_broadwater: no is_crestline: no is_ivybridge: no is_valleyview: no is_haswell: yes is_skylake: no is_preliminary: no has_fbc: yes has_pipe_cxsr: no has_hotplug: yes cursor_needs_physical: no has_overlay: no overlay_needs_physical: no supports_tv: no has_llc: yes has_ddi: yes has_fpga_dbg: yes
I presume the difference is that sna disables the primary plane on the CRTCs prior to VT switch (so that we do not leak information to the next client). If you did diff --git a/src/sna/sna_display.c b/src/sna/sna_display.c index 53eb9ca..af44dbc 100644 --- a/src/sna/sna_display.c +++ b/src/sna/sna_display.c @@ -7347,6 +7347,7 @@ void sna_mode_reset(struct sna *sna) xf86CrtcConfigPtr config = XF86_CRTC_CONFIG_PTR(sna->scrn); int i; + return; if (sna->flags & SNA_IS_HOSTED) return; then you will get the same behaviour in sna as uxa on VT switch.
Yes, this fixes it.
Chris, planning on doing something about this?
(In reply to Jani Nikula from comment #3) > Chris, planning on doing something about this? What? It's a kernel bug.
(In reply to Chris Wilson from comment #4) > (In reply to Jani Nikula from comment #3) > > Chris, planning on doing something about this? > > What? It's a kernel bug. Sorry, was browsing the bugs a tad too fast. I take that as a "no". ;)
David, can you, uh, check if we've maybe done something about this, intentionally or otherwise...?
Reporter or Chris, is this still valid issue?
Looks like it was a kernel bug, but fixed with Chris suggestion, also pretty old with no recent activity
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