In its current place, it just segfaults while trying to access the
CRTC structures:
[ 9132.421681] Call Trace:
[ 9132.421707] [<ffffffffa01130d8>] i915_get_crtc_scanoutpos+0x1e8/0x220 [i915]
[ 9132.421727] [<ffffffffa001da34>] drm_calc_vbltimestamp_from_scanoutpos+0x94/0x330 [drm]
[ 9132.421744] [<ffffffffa001d240>] ?vblank_disable_and_save+0x40/0x1e0 [drm]
[ 9132.421769] [<ffffffffa0114328>] i915_get_vblank_timestamp+0x68/0xb0 [i915]
[ 9132.421786] [<ffffffffa001d094>] drm_get_last_vbltimestamp+0x44/0x80 [drm]
[ 9132.421801] [<ffffffffa001d3a6>] vblank_disable_and_save+0x1a6/0x1e0 [drm]
[ 9132.421817] [<ffffffffa001eac1>] drm_vblank_cleanup+0x61/0xa0 [drm]
[ 9132.421849] [<ffffffffa0177a5e>] i915_driver_unload+0xde/0x290 [i915]
[ 9132.421867] [<ffffffffa0020264>] drm_dev_unregister+0x24/0xb0 [drm]
[ 9132.421884] [<ffffffffa002090e>] drm_put_dev+0x1e/0x70 [drm]
[ 9132.421901] [<ffffffffa00e01e0>] i915_pci_remove+0x10/0x20 [i915]
[ 9132.421910] [<ffffffff81347556>] pci_device_remove+0x36/0xb0
[ 9132.421920] [<ffffffff8140084a>] __device_release_driver+0x7a/0xf0
[ 9132.421928] [<ffffffff81400fc8>] driver_detach+0xb8/0xc0
[ 9132.421936] [<ffffffff8140054a>] bus_remove_driver+0x4a/0xb0
[ 9132.421944] [<ffffffff81401717>] driver_unregister+0x27/0x50
[ 9132.421953] [<ffffffff81346f65>] pci_unregister_driver+0x25/0x70
[ 9132.421971] [<ffffffffa00229c8>] drm_pci_exit+0x78/0xa0 [drm]
[ 9132.422000] [<ffffffffa017a6d2>] i915_exit+0x20/0x94e [i915]
[ 9132.422009] [<ffffffff810fb9dc>] SyS_delete_module+0x13c/0x1f0
[ 9132.422019] [<ffffffff8131c5fb>] ?
trace_hardirqs_on_thunk+0x3a/0x3f
[ 9132.422028] [<ffffffff816f7792>] system_call_fastpath+0x16/0x1b
This means it has to be before intel_modeset_cleanup, which cleans the
CRTC structures. But if we move it to before intel_fbdev_fini(), we
get WARNs because intel_fbdev_fini() still tries to use the vblanks,
so the only acceptable point for drm_vblank_cleanup() seems to be this
place.
Related commit:
commit cbb47d179f
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Mon Sep 23 17:33:20 2013 -0300
drm/i915: Add some missing steps to i915_driver_load error path
Testsuite: igt/drv_module_reload
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=77511
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=83484
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
************************************************************
* For the very latest on DRI development, please see: *
* http://dri.freedesktop.org/ *
************************************************************
The Direct Rendering Manager (drm) is a device-independent kernel-level
device driver that provides support for the XFree86 Direct Rendering
Infrastructure (DRI).
The DRM supports the Direct Rendering Infrastructure (DRI) in four major
ways:
1. The DRM provides synchronized access to the graphics hardware via
the use of an optimized two-tiered lock.
2. The DRM enforces the DRI security policy for access to the graphics
hardware by only allowing authenticated X11 clients access to
restricted regions of memory.
3. The DRM provides a generic DMA engine, complete with multiple
queues and the ability to detect the need for an OpenGL context
switch.
4. The DRM is extensible via the use of small device-specific modules
that rely extensively on the API exported by the DRM module.
Documentation on the DRI is available from:
http://dri.freedesktop.org/wiki/Documentation
http://sourceforge.net/project/showfiles.php?group_id=387
http://dri.sourceforge.net/doc/
For specific information about kernel-level support, see:
The Direct Rendering Manager, Kernel Support for the Direct Rendering
Infrastructure
http://dri.sourceforge.net/doc/drm_low_level.html
Hardware Locking for the Direct Rendering Infrastructure
http://dri.sourceforge.net/doc/hardware_locking_low_level.html
A Security Analysis of the Direct Rendering Infrastructure
http://dri.sourceforge.net/doc/security_low_level.html
2ebfaf5f10