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Chris Wilson e0da1963fe drm/i915: Short-circuit i915_gem_wait_for_idle() if already idle
If the device is asleep (no GT wakeref), we know the GPU is already idle.
If we add an early return, we can avoid touching registers and checking
hw state outside of the assumed GT wakelock. This prevents causing such
errors whilst debugging:

[ 2613.401647] RPM wakelock ref not held during HW access
[ 2613.401684] ------------[ cut here ]------------
[ 2613.401720] WARNING: CPU: 5 PID: 7739 at drivers/gpu/drm/i915/intel_drv.h:1787 gen6_read32+0x21f/0x2b0 [i915]
[ 2613.401731] Modules linked in: snd_hda_intel i915 vgem snd_hda_codec_hdmi x86_pkg_temp_thermal intel_powerclamp snd_hda_codec_realtek coretemp snd_hda_codec_generic crct10dif_pclmul crc32_pclmul ghash_clmulni_intel snd_hda_codec snd_hwdep snd_hda_core snd_pcm r8169 mii mei_me lpc_ich mei prime_numbers [last unloaded: i915]
[ 2613.401823] CPU: 5 PID: 7739 Comm: drv_missed_irq Tainted: G     U          4.12.0-rc2-CI-CI_DRM_421+ #1
[ 2613.401825] Hardware name: MSI MS-7924/Z97M-G43(MS-7924), BIOS V1.12 02/15/2016
[ 2613.401840] task: ffff880409e3a740 task.stack: ffffc900084dc000
[ 2613.401861] RIP: 0010:gen6_read32+0x21f/0x2b0 [i915]
[ 2613.401863] RSP: 0018:ffffc900084dfce8 EFLAGS: 00010292
[ 2613.401869] RAX: 000000000000002a RBX: ffff8804016a8000 RCX: 0000000000000006
[ 2613.401871] RDX: 0000000000000006 RSI: ffffffff81cbf2d9 RDI: ffffffff81c9e3a7
[ 2613.401874] RBP: ffffc900084dfd18 R08: ffff880409e3afc8 R09: 0000000000000000
[ 2613.401877] R10: 000000008a1c483f R11: 0000000000000000 R12: 000000000000209c
[ 2613.401879] R13: 0000000000000001 R14: ffff8804016a8000 R15: ffff8804016ac150
[ 2613.401882] FS:  00007f39ef3dd8c0(0000) GS:ffff88041fb40000(0000) knlGS:0000000000000000
[ 2613.401885] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 2613.401887] CR2: 00000000023717c8 CR3: 00000002e7b34000 CR4: 00000000001406e0
[ 2613.401889] Call Trace:
[ 2613.401912]  intel_engine_is_idle+0x76/0x90 [i915]
[ 2613.401931]  i915_gem_wait_for_idle+0xe6/0x1e0 [i915]
[ 2613.401951]  fault_irq_set+0x40/0x90 [i915]
[ 2613.401970]  i915_ring_test_irq_set+0x42/0x50 [i915]
[ 2613.401976]  simple_attr_write+0xc7/0xe0
[ 2613.401981]  full_proxy_write+0x4f/0x70
[ 2613.401987]  __vfs_write+0x23/0x120
[ 2613.401992]  ? rcu_read_lock_sched_held+0x75/0x80
[ 2613.401996]  ? rcu_sync_lockdep_assert+0x2a/0x50
[ 2613.401999]  ? __sb_start_write+0xfa/0x1f0
[ 2613.402004]  vfs_write+0xc5/0x1d0
[ 2613.402008]  ? trace_hardirqs_on_caller+0xe7/0x1c0
[ 2613.402013]  SyS_write+0x44/0xb0
[ 2613.402020]  entry_SYSCALL_64_fastpath+0x1c/0xb1
[ 2613.402022] RIP: 0033:0x7f39eded6670
[ 2613.402025] RSP: 002b:00007fffdcdcb1a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[ 2613.402030] RAX: ffffffffffffffda RBX: ffffffff81470203 RCX: 00007f39eded6670
[ 2613.402033] RDX: 0000000000000001 RSI: 000000000041bc33 RDI: 0000000000000006
[ 2613.402036] RBP: ffffc900084dff88 R08: 00007f39ef3dd8c0 R09: 0000000000000001
[ 2613.402038] R10: 0000000000000000 R11: 0000000000000246 R12: 000000000041bc33
[ 2613.402041] R13: 0000000000000006 R14: 0000000000000000 R15: 0000000000000000
[ 2613.402046]  ? __this_cpu_preempt_check+0x13/0x20
[ 2613.402052] Code: 01 9b fa e0 0f ff e9 28 fe ff ff 80 3d 6a dd 0e 00 00 0f 85 29 fe ff ff 48 c7 c7 48 19 29 a0 c6 05 56 dd 0e 00 01 e8 da 9a fa e0 <0f> ff e9 0f fe ff ff b9 01 00 00 00 ba 01 00 00 00 44 89 e6 48
[ 2613.402199] ---[ end trace 31f0cfa93ab632bf ]---

Fixes: 25112b64b3 ("drm/i915: Wait for all engines to be idle as part of i915_gem_wait_for_idle()")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170530121334.17364-1-chris@chris-wilson.co.uk
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
(cherry picked from commit 863e9fde1a)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
2017-06-07 16:30:54 +03:00
arch Merge branch 'akpm' (patches from Andrew) 2017-06-02 15:49:46 -07:00
block block: Avoid that blk_exit_rl() triggers a use-after-free 2017-06-01 13:07:55 -06:00
certs scripts/spelling.txt: add "intialise(d)" pattern and fix typo instances 2017-05-08 17:15:13 -07:00
crypto crypto: skcipher - Add missing API setkey checks 2017-05-18 13:04:05 +08:00
Documentation Pin control fixes for v4.12: 2017-05-29 10:05:19 -07:00
drivers drm/i915: Short-circuit i915_gem_wait_for_idle() if already idle 2017-06-07 16:30:54 +03:00
firmware firmware/Makefile: force recompilation if makefile changes 2017-05-08 17:15:10 -07:00
fs fs/ufs: Set UFS default maximum bytes per file 2017-06-04 16:33:54 -07:00
include Fixes for 4.12-rc 2017-06-04 10:41:32 -07:00
init Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-05-10 10:30:46 -07:00
ipc mm: introduce kv[mz]alloc helpers 2017-05-08 17:15:12 -07:00
kernel Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching 2017-06-02 08:59:17 -07:00
lib test_bpf: Add a couple of tests for BPF_JSGE. 2017-05-25 14:37:56 -04:00
mm mm: consider memblock reservations for deferred memory initialization sizing 2017-06-02 15:07:38 -07:00
net NFS client bugfixes for Linux 4.12 2017-06-04 11:56:53 -07:00
samples samples/bpf: run cleanup routines when receiving SIGTERM 2017-05-11 21:43:30 -04:00
scripts scripts/gdb: make lx-dmesg command work (reliably) 2017-06-02 15:07:38 -07:00
security Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-05-09 09:12:53 -07:00
sound sound fixes for 4.12-rc4 2017-06-02 09:40:47 -07:00
tools powerpc fixes for 4.12 #4 2017-05-27 09:28:34 -07:00
usr initramfs: fix disabling of initramfs (and its compression) 2017-06-02 15:07:37 -07:00
virt KVM: arm/arm64: Hold slots_lock when unregistering kvm io bus devices 2017-05-18 11:18:16 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: Add support to generate LLVM assembly files 2017-04-25 08:13:52 +09:00
.mailmap power supply and reset changes for the v4.12 series (part 2) 2017-05-12 12:02:21 -07:00
COPYING
CREDITS avr32: remove support for AVR32 architecture 2017-05-01 09:27:15 +02:00
Kbuild kbuild: Consolidate header generation from ASM offset information 2017-04-13 05:43:37 +09:00
Kconfig
MAINTAINERS RTC for 4.12 #2 2017-06-04 11:29:32 -07:00
Makefile Linux 4.12-rc4 2017-06-04 16:47:43 -07:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

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.