Re: [Bug 214725] New: simpledrm and i915 both active after boot

Hi

Am 15.10.21 um 01:28 schrieb bugzilla-daemon@bugzilla.kernel.org:

https://bugzilla.kernel.org/show_bug.cgi?id=214725

         Bug ID: 214725
        Summary: simpledrm and i915 both active after boot
        Product: Drivers
        Version: 2.5
 Kernel Version: 5.14.11
       Hardware: All
             OS: Linux
           Tree: Mainline
         Status: NEW
       Severity: normal
       Priority: P1
      Component: Video(DRI - non Intel)
       Assignee: drivers_video-dri@kernel-bugs.osdl.org
       Reporter: dennis.lissov@gmail.com
     Regression: No

Gentoo Linux, custom kernel build, 5.14.11 with CONFIG_DRM_SIMPLEDRM=y CONFIG_DRM_I915=y

Plasma (wayland) sees two monitors: the laptop screen and an unknown one. The only monitor physically present is the laptop screen. This did not happen a few months ago (possibly started with 5.14 upgrade).

$ ls /sys/class/drm/ card0 card0-eDP-1 card1 card1-Unknown-1 card2 card2-DP-1 card2-DP-2 card2-DP-3 renderD128 renderD129 version $ readlink /sys/class/drm/card0 # Intel GPU ../../devices/pci0000:00/0000:00:02.0/drm/card0 $ readlink /sys/class/drm/card1 # Simple DRM ../../devices/platform/simple-framebuffer.0/drm/card1 $ readlink /sys/class/drm/card2 # Nouveau (not used at the moment) ../../devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card2

$ dmesg | egrep '(simple|i915)' [ 0.000000] Command line: BOOT_IMAGE=/kernel-5.14.11 root=[...] ro acpi_backlight=video resume=[...] i915.enable_gvt=1 quiet [ 0.060342] Kernel command line: BOOT_IMAGE=/kernel-5.14.11 root=[...] ro acpi_backlight=video resume=[...] i915.enable_gvt=1 quiet [ 1.076957] i915 0000:00:02.0: [drm] VT-d active for gfx access [ 1.076961] i915 0000:00:02.0: vgaarb: deactivate vga console [ 1.387359] i915 0000:00:02.0: Direct firmware load for i915/gvt/vid_0x8086_did_0x191b_rid_0x06.golden_hw_state failed with error -2 [ 1.404418] i915 0000:00:02.0: vgaarb: changed VGA decodes: olddecodes=io+mem,decodes=none:owns=io+mem [ 1.404525] i915 0000:00:02.0: [drm] Disabling framebuffer compression (FBC) to prevent screen flicker with VT-d enabled [ 1.404931] i915 0000:00:02.0: [drm] Finished loading DMC firmware i915/skl_dmc_ver1_27.bin (v1.27) [ 1.422128] [drm] Initialized i915 1.6.0 20201103 for 0000:00:02.0 on minor 0 [ 1.425127] [drm] Initialized simpledrm 1.0.0 20200625 for simple-framebuffer.0 on minor 1 [ 1.437859] simple-framebuffer simple-framebuffer.0: [drm] fb0: simpledrm frame buffer device [ 1.438058] fbcon: i915 (fb1) is primary device [ 2.579133] i915 0000:00:02.0: [drm] fb1: i915 frame buffer device [ 22.162612] snd_hda_intel 0000:00:1f.3: bound 0000:00:02.0 (ops i915_audio_component_bind_ops) [ 52.106084] simple-framebuffer simple-framebuffer.0: swiotlb buffer is full (sz: 8388608 bytes), total 32768 (slots), used 0 (slots)

Looks like the hand-over mechanism does not correctly handle this combination, possibly due to i915 loading before simpledrm.

Interesting. There are two workarounds:

* build every driver except simpledrm as module, or * don't build simpledrm on yur system (it's Gentoo)

I don't think that linking all driver into the kernel worked before simpledrm. Before simpledrm there would be simplefb, efifb or vesafb. Those drivers use a similar handover scheme, which would have failed in a similar way.

Best regards Thomas