96dabe99ca
The busy-spin, as the first stage of intel_wait_for_register(), is currently under suspicion for causing: [ 62.034926] NMI watchdog: Watchdog detected hard LOCKUP on cpu 1 [ 62.034928] Modules linked in: i2c_dev i915 intel_gtt drm_kms_helper prime_numbers [ 62.034932] CPU: 1 PID: 183 Comm: kworker/1:2 Not tainted 4.11.0-rc7+ #471 [ 62.034933] Hardware name: / , BIOS PYBSWCEL.86A.0027.2015.0507.1758 05/07/2015 [ 62.034934] Workqueue: pm pm_runtime_work [ 62.034936] task: ffff880275a04ec0 task.stack: ffffc900002d8000 [ 62.034936] RIP: 0010:__intel_wait_for_register_fw+0x77/0x1a0 [i915] [ 62.034937] RSP: 0018:ffffc900002dbc38 EFLAGS: 00000082 [ 62.034939] RAX: ffffc90003530094 RBX: 0000000000130094 RCX: 0000000000000001 [ 62.034940] RDX: 00000000000000a1 RSI: ffff88027fd15e58 RDI: 0000000000000000 [ 62.034941] RBP: ffffc900002dbc78 R08: 0000000000000002 R09: 0000000000000000 [ 62.034942] R10: ffffc900002dbc18 R11: ffff880276429dd0 R12: ffff8802707c0000 [ 62.034943] R13: 00000000000000a0 R14: 0000000000000000 R15: 00000000fffefc10 [ 62.034945] FS: 0000000000000000(0000) GS:ffff88027fd00000(0000) knlGS:0000000000000000 [ 62.034945] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 62.034947] CR2: 00007ffd3cd98ff8 CR3: 0000000274c19000 CR4: 00000000001006e0 [ 62.034947] Call Trace: [ 62.034948] intel_wait_for_register+0x77/0x140 [i915] [ 62.034949] vlv_suspend_complete+0x23/0x5b0 [i915] [ 62.034950] intel_runtime_suspend+0x16c/0x2a0 [i915] [ 62.034950] pci_pm_runtime_suspend+0x50/0x180 [ 62.034951] ? pci_pm_runtime_resume+0xa0/0xa0 [ 62.034952] __rpm_callback+0xc5/0x210 [ 62.034953] rpm_callback+0x1f/0x80 [ 62.034953] ? pci_pm_runtime_resume+0xa0/0xa0 [ 62.034954] rpm_suspend+0x118/0x580 [ 62.034955] pm_runtime_work+0x64/0x90 [ 62.034956] process_one_work+0x1bb/0x3e0 [ 62.034956] worker_thread+0x46/0x4f0 [ 62.034957] ? __schedule+0x18b/0x610 [ 62.034958] kthread+0xff/0x140 [ 62.034958] ? process_one_work+0x3e0/0x3e0 [ 62.034959] ? kthread_create_on_node+ and related hard lockups in CI for byt and bsw. Note this effectively reverts commits 41ce405e6894 and b27366958869 ("drm/i915: Convert wait_for(I915_READ(reg)) to intel_wait_for_register()") v2: Convert bool allow into a u32 mask for clarity and repeat the comment on vlv rc6 timing to justify the 3ms timeout used for the wait (Ville) Fixes: 41ce405e6894 ("drm/i915: Convert wait_for(I915_READ(reg)) to intel_wait_for_register()") Fixes: b27366958869 ("drm/i915: Convert wait_for(I915_READ(reg)) to intel_wait_for_register()") Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=100718 Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Tomi Sarvela <tomi.p.sarvela@intel.com> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20170421135815.11897-1-chris@chris-wilson.co.uk Tested-by: Tomi Sarvela <tomi.p.sarvela@intel.com> (cherry picked from commit 3dd14c04d77d7d702de5aa7157df4cc9417329f3) Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.