Bug 106804

From strace:

1880  ioctl(14, DRM_IOCTL_I915_GEM_MMAP <unfinished ...>
1895  <... read resumed> 0x2163e98, 7752) = -1 EAGAIN (Resource temporarily unavailable)
1880  <... ioctl resumed> , 0x7ffe47fdf6b0) = 0
1895  read(37, 0x2163e80, 7776)         = -1 EAGAIN (Resource temporarily unavailable)
1895  read(37, 0x2163e68, 7800)         = -1 EAGAIN (Resource temporarily unavailable)
1895  read(37,  <unfinished ...>
1880  ioctl(16, DRM_IOCTL_MODE_LIST_LESSEES <unfinished ...>
1895  <... read resumed> 0x2163e50, 7824) = -1 EAGAIN (Resource temporarily unavailable)
1880  <... ioctl resumed> , 0x7ffe47fdf9a0) = 0
1880  ioctl(16, DRM_IOCTL_MODE_LIST_LESSEES, 0x7ffe47fdf9a0) = 0
1880  ioctl(14, DRM_IOCTL_MODE_DIRTYFB, 0x7ffe47fdf980) = -1 ENOENT (No such file or directory)
1880  ioctl(14, DRM_IOCTL_MODE_SETGAMMA <unfinished ...>
1895  write(22, "\0", 1)                = 1
1895  epoll_wait(25,  <unfinished ...>
1880  <... ioctl resumed> , 0x7ffe47fdf8e0) = 0
1880  ioctl(14, DRM_IOCTL_MODE_ADDFB2, 0x7ffe47fdf6e0) = 0
1880  ioctl(14, DRM_IOCTL_MODE_CREATEPROPBLOB, 0x7ffe47fdf740) = 0
1880  ioctl(14, DRM_IOCTL_MODE_ATOMIC, 0x7ffe47fdf7f0) = -1 EINVAL (Invalid argument)
1880  write(4, "[   126.170] ", 13)     = 13
1880  write(4, "(EE) modeset(0): failed to set mode: Invalid argument\n", 54) = 54
1880  epoll_wait(3, [{EPOLLIN, {u32=31794656, u64=31794656}}], 256, 599996) = 1

drm.debug=0x1f ?

Created attachment 140001 [details]
dmesg with debug

That was done back then but with 0xe, is that enough?

0x1f gives slightly more useful information.

Created attachment 140003 [details]
drm debug 0x1f

Do you happen to have the Xorg log from the same run? I want to see the timing of Xorg.0.log versus that dmesg, so I can see where it fails exactly on what call.

hm then again guessing it's the first atomic call that fails with -22, probably in drm_mode_convert_umode from drm_atomic_set_mode_prop_for_crtc.

Probably intel_mode_valid that fails, could you dump mode->flags ?

Oh nm, the clue is in the Xorg log..

[   123.751] (II) modeset(0): Printing probed modes for output eDP-1
[   123.751] (II) modeset(0): Modeline "1920x1080"x120.0  356.38  1920 2080 2288 2656  1080 1081 1084 1118 doublescan -hsync +vsync (134.2 kHz UdP)
[   123.751] (II) modeset(0): Modeline "3200x1800"x60.0  373.25  3200 3248 3280 3360  1800 1803 1808 1852 -hsync -vsync (111.1 kHz eP)
[   123.751] (II) modeset(0): Modeline "3200x1800"x60.0  492.00  3200 3456 3800 4400  1800 1803 1808 1865 -hsync +vsync (111.8 kHz d)
[   123.751] (II) modeset(0): Modeline "3200x1800"x59.9  373.00  3200 3248 3280 3360  1800 1803 1808 1852 +hsync -vsync (111.0 kHz d)

doublescan being set somehow..

Possibly fixed by:
https://patchwork.freedesktop.org/patch/225189/

The bigger mystery is why modesetting would default to a dblscan mode. That makes no sense. Sadly our debugs for atomic are woefully inadequate so the logs don't contain the reason for the failure :(

That patch fixes it for me.

No xorg.log from the same run but can make it if needed.

btw. this laptop has native 3200x1800 screen resolution but I'm using:

               Modes   "1920x1080"

in xorg.conf

Ah, that is the missing piece why it chooses that mode.
X.org is borked and just sets doublescan/interlaced is always possible with modesetting:
    output->interlaceAllowed = TRUE;
    output->doubleScanAllowed = TRUE;

And because it has the highest clock, you get your 1920 mode with doublescan..

(In reply to Maarten Lankhorst from comment #13)
> Ah, that is the missing piece why it chooses that mode.
> X.org is borked and just sets doublescan/interlaced is always possible with
> modesetting:
>     output->interlaceAllowed = TRUE;
>     output->doubleScanAllowed = TRUE;
> 
> And because it has the highest clock, you get your 1920 mode with
> doublescan..

Also the mode flags aren't even checked by the xf86DefaulltModes stuff. So even if we set doubleScanAllowed=FALSE we'd still get doublescan modes in the list :(

commit e4dd27aadd205417a2e9ea9902b698a0252ec3a0
Author: Ville Syrjälä <ville.syrjala@linux.intel.com>
Date:   Thu May 24 15:54:03 2018 +0300

    drm/i915: Allow DBLSCAN user modes with eDP/LVDS/DSI

Push it to -stable please.

(In reply to Arkadiusz Miskiewicz from comment #16)
> Push it to -stable please.

The patch has cc:stable, so it'll get there eventually.