[Intel-gfx] i915.fastboot bug report - not working on coreboot

[Charles Devereaux]

Hello

I'm trying to use i915.fastboot on a Thinkpad X60t. The bios has been
replaced by coreboot, which supports native video init.

The goal is to boot to a console on a debian in less than 2 seconds (kernel
+ systemd), systemd is just fine in 0.6s but the kernel takes a long time,
with apparently 1 full second spend on the video mode initialization, just
as if fastboot was ignored.

Coreboot is starting a grub2 payload, which is in the appropriate vesa
mode, and has option set gfxpayload=keep to pass it to the kernel.

The 3.14.16 kernel start in the appropriate vesa mode, but there is some
flickering at one time, which indicates the drivers tries to reinitialize
the video card, before returning to this same mode.

The kernel arguments are:
nohz=on nmi_watchdog=0 pcie_aspm=force i915.semaphores=1 i915.fastboot=1
i915.i915_enable_rc6=7 i915.i915_enable_fbc=1 i915.lvds_downclock=1
thinkpad_acpi.force_load=1 thinkpad_acpi.brightness_enable=0
snd-hda-intel.index=0 snd_hda_intel.power_save=10
snd_hda_intel.model=thinkpad snd-hda-intel.probe_mask=0x103
snd-pcsp.index=1 btusb.reset=1 quiet root=/dev/sda1

The kernel .config has:
CONFIG_DRM_I915=y
CONFIG_DRM_I915_KMS=y
CONFIG_DRM_I915_FBDEV=y
# CONFIG_DRM_I915_PRELIMINARY_HW_SUPPORT is not set
# CONFIG_DRM_I915_UMS is not set

Is it possible to enable some kind of debugging of i915.fastboot to see why
exactly the video is reinitialized?

I didn't see any module option to do that in drivers/gpu/drm/i915/i915_drv.c

Here are the dmesg showing the time spent.

In a 3.14.16 kernel :
[    0.498511] [drm] Initialized drm 1.1.0 20060810
[    0.498967] [drm] Memory usable by graphics device = 256M
[    0.500365] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[    0.500370] [drm] Driver supports precise vblank timestamp query.
[    0.500377] i915 0000:00:02.0: Invalid ROM contents
[    0.500384] [drm] failed to find VBIOS tables
[    0.500449] vgaarb: device changed decodes:
PCI:0000:00:02.0,olddecodes=io+me
m,decodes=io+mem:owns=io+mem
[    0.532092] [drm] initialized overlay support
[    0.799483] fbcon: inteldrmfb (fb0) is primary device
[    1.452009] Console: switching to colour frame buffer device 128x48
[    1.480975] i915 0000:00:02.0: fb0: inteldrmfb frame buffer device
[    1.480978] i915 0000:00:02.0: registered panic notifier
[    1.480990] [drm] Initialized i915 1.6.0 20080730 for 0000:00:02.0 on
minor 0


In a 3.10.45 kernel: (no fastboot support)
[    0.213937] [drm] Initialized drm 1.1.0 20060810
[    0.214643] [drm] Memory usable by graphics device = 256M
[    0.214650] i915 0000:00:02.0: setting latency timer to 64
[    0.216252] [drm] Supports vblank timestamp caching Rev 1 (10.10.2010).
[    0.216284] [drm] Driver supports precise vblank timestamp query.
[    0.216291] i915 0000:00:02.0: Invalid ROM contents
[    0.216298] [drm] failed to find VBIOS tables
[    0.216351] vgaarb: device changed decodes:
PCI:0000:00:02.0,olddecodes=io+mem,decodes=io+mem:owns=io+mem
[    0.226207] ACPI: Deprecated procfs I/F for battery is loaded, please
retry with CONFIG_ACPI_PROCFS_POWER cleared
[    0.226218] ACPI: Battery Slot [BAT0] (battery present)
[    0.226378] ACPI: Deprecated procfs I/F for battery is loaded, please
retry with CONFIG_ACPI_PROCFS_POWER cleared
[    0.226386] ACPI: Battery Slot [BAT1] (battery absent)
[    0.267013] [drm] GMBUS [i915 gmbus panel] timed out, falling back to
bit banging on pin 3
[    0.297928] [drm] initialized overlay support
[    0.360013] [drm] GMBUS [i915 gmbus vga] timed out, falling back to bit
banging on pin 2
[    0.546070] fbcon: inteldrmfb (fb0) is primary device
[    1.198025] Console: switching to colour frame buffer device 128x48
[    1.226996] i915 0000:00:02.0: fb0: inteldrmfb frame buffer device
[    1.227000] i915 0000:00:02.0: registered panic notifier
[    1.227015] [drm] Initialized i915 1.6.0 20080730 for 0000:00:02.0 on
minor 0
[    1.228648] loop: module loaded
[    1.279013] [drm] GMBUS [i915 gmbus ssc] timed out, falling back to bit
banging on pin 1
[    1.398013] [drm] GMBUS [i915 gmbus dpc] timed out, falling back to bit
banging on pin 4
[    1.513013] [drm] GMBUS [i915 gmbus dpb] timed out, falling back to bit
banging on pin 5
[    1.586013] [drm] GMBUS [i915 gmbus dpd] timed out, falling back to bit
banging on pin 6

Thanks
Charles
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