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Chris Wilson 0b702dca26 drm/i915: Avoid waking the engines just to check if they are idle
Exploit that reads of the ring registers return 0 from the engine when
it is idle and we do not apply forcewake to know that if the engine is
idle then both reads will be identical (and so we interpret the ring as
idle).

The ulterior motive is to try and reduce the number of spurious wakeups
to avoid untimely death, such as:

<3> [85.046836] [drm:fw_domains_get [i915]] *ERROR* render: timed out waiting for forcewake ack request.
<4> [85.051916] ------------[ cut here ]------------
<4> [85.051917] GT thread status wait timed out
<4> [85.051963] WARNING: CPU: 2 PID: 2195 at drivers/gpu/drm/i915/intel_uncore.c:303 __gen6_gt_wait_for_thread_c0+0x6e/0xa0 [i915]
<4> [85.051964] Modules linked in: snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic i915 x86_pkg_temp_thermal coretemp mei_hdcp crct10dif_pclmul crc32_pclmul snd_hda_intel ghash_clmulni_intel snd_hda_codec broadcom bcm_phy_lib i2c_i801 snd_hwdep snd_hda_core tg3 snd_pcm ptp pps_core mei_me mei prime_numbers lpc_ich
<4> [85.051980] CPU: 2 PID: 2195 Comm: drm_read Tainted: G     U            5.0.0-rc8-CI-CI_DRM_5662+ #1
<4> [85.051981] Hardware name: Dell Inc. XPS 8300  /0Y2MRG, BIOS A06 10/17/2011
<4> [85.052012] RIP: 0010:__gen6_gt_wait_for_thread_c0+0x6e/0xa0 [i915]
<4> [85.052015] Code: 8b 92 5c 80 13 00 83 e2 07 75 d5 5b 5d c3 80 3d 5b 6a 1a 00 00 75 f4 48 c7 c7 38 21 31 a0 c6 05 4b 6a 1a 00 01 e8 e2 84 ea e0 <0f> 0b eb dd 80 3d 3a 6a 1a 00 00 75 98 48 c7 c6 08 21 31 a0 48 c7
<4> [85.052016] RSP: 0018:ffffc9000043bd00 EFLAGS: 00010086
<4> [85.052019] RAX: 0000000000000000 RBX: ffff888217c50000 RCX: 0000000000000000
<4> [85.052020] RDX: 0000000000000007 RSI: ffffffff820cb141 RDI: 00000000ffffffff
<4> [85.052022] RBP: 00000013cd30f2fb R08: 0000000000000000 R09: 0000000000000001
<4> [85.052024] R10: ffffc9000043bce0 R11: 0000000000000000 R12: ffff888217c50ee0
<4> [85.052025] R13: 0000000000000001 R14: 00000000ffffffff R15: ffff888218076530
<4> [85.052028] FS:  00007fc79d049980(0000) GS:ffff888227a80000(0000) knlGS:0000000000000000
<4> [85.052029] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
<4> [85.052031] CR2: 00007f782e2940f8 CR3: 000000022458e006 CR4: 00000000000606e0
<4> [85.052033] Call Trace:
<4> [85.052064]  gen6_read32+0x14e/0x250 [i915]
<4> [85.052096]  intel_engine_is_idle+0x7d/0x180 [i915]
<4> [85.052126]  intel_engines_are_idle+0x29/0x50 [i915]
<4> [85.052153]  i915_drop_caches_set+0x21c/0x290 [i915]
<4> [85.052160]  simple_attr_write+0xb0/0xd0
<4> [85.052165]  full_proxy_write+0x51/0x80
<4> [85.052170]  __vfs_write+0x31/0x190
<4> [85.052176]  ? rcu_read_lock_sched_held+0x6f/0x80
<4> [85.052178]  ? rcu_sync_lockdep_assert+0x29/0x50
<4> [85.052181]  ? __sb_start_write+0x152/0x1f0
<4> [85.052183]  ? __sb_start_write+0x163/0x1f0
<4> [85.052187]  vfs_write+0xbd/0x1b0
<4> [85.052191]  ksys_write+0x50/0xc0
<4> [85.052196]  do_syscall_64+0x55/0x190
<4> [85.052200]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
<4> [85.052202] RIP: 0033:0x7fc79c9d3281
<4> [85.052204] Code: c3 0f 1f 84 00 00 00 00 00 48 8b 05 59 8d 20 00 c3 0f 1f 84 00 00 00 00 00 8b 05 8a d1 20 00 85 c0 75 16 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 57 f3 c3 0f 1f 44 00 00 41 54 55 49 89 d4 53
<4> [85.052206] RSP: 002b:00007fffa4a0a7f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
<4> [85.052208] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007fc79c9d3281
<4> [85.052210] RDX: 0000000000000005 RSI: 00007fffa4a0a880 RDI: 0000000000000008
<4> [85.052212] RBP: 00007fffa4a0a820 R08: 0000000000000000 R09: 0000000000000000
<4> [85.052213] R10: 0000000000000000 R11: 0000000000000246 R12: 00007fc79c9bc718
<4> [85.052215] R13: 0000000000000003 R14: 00007fc79c9c1628 R15: 00007fc79c9bdd80
<4> [85.052223] irq event stamp: 71630
<4> [85.052226] hardirqs last  enabled at (71629): [<ffffffff8197b64c>] _raw_spin_unlock_irqrestore+0x4c/0x60
<4> [85.052228] hardirqs last disabled at (71630): [<ffffffff8197b4bd>] _raw_spin_lock_irqsave+0xd/0x50
<4> [85.052231] softirqs last  enabled at (70444): [<ffffffff81c0033a>] __do_softirq+0x33a/0x4b9
<4> [85.052234] softirqs last disabled at (70433): [<ffffffff810b51b1>] irq_exit+0xd1/0xe0
<4> [85.052264] WARNING: CPU: 2 PID: 2195 at drivers/gpu/drm/i915/intel_uncore.c:303 __gen6_gt_wait_for_thread_c0+0x6e/0xa0 [i915]

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190227114958.32438-1-chris@chris-wilson.co.uk
2019-02-27 15:29:26 +00:00
arch Merge branch 'efi-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-02-17 09:22:01 -08:00
block for-linus-20190215 2019-02-15 09:12:28 -08:00
certs kbuild: remove redundant target cleaning on failure 2019-01-06 09:46:51 +09:00
crypto crypto: sm3 - fix undefined shift by >= width of value 2019-01-10 21:37:32 +08:00
Documentation Prep patches + headers for the mei-hdcp/i915 component interfaces 2019-02-20 11:53:48 +02:00
drivers drm/i915: Avoid waking the engines just to check if they are idle 2019-02-27 15:29:26 +00:00
firmware kbuild: change filechk to surround the given command with { } 2019-01-06 09:46:51 +09:00
fs Two small fixes, one for crashes using nfs/krb5 with older enctypes, one 2019-02-16 17:38:01 -08:00
include drm: removing the DP Errata msg and its msg id 2019-02-20 20:41:30 +01:00
init Revert "mm: use early_pfn_to_nid in page_ext_init" 2019-02-12 16:33:18 -08:00
ipc ipc: IPCMNI limit check for semmni 2018-10-31 08:54:14 -07:00
kernel Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-02-17 08:38:13 -08:00
lib Compiler Attributes: Clean the new GCC 9 -Wmissing-attributes warnings 2019-02-16 10:28:05 -08:00
LICENSES This is a fairly typical cycle for documentation. There's some welcome 2018-10-24 18:01:11 +01:00
mm arm64, mm, efi: Account for GICv3 LPI tables in static memblock reserve table 2019-02-16 15:02:03 +01:00
net Two small fixes, one for crashes using nfs/krb5 with older enctypes, one 2019-02-16 17:38:01 -08:00
samples samples: mei: use /dev/mei0 instead of /dev/mei 2019-01-30 15:24:45 +01:00
scripts Bug fixes for gcc-plugins 2019-01-21 13:07:03 +13:00
security apparmor: Fix aa_label_build() error handling for failed merges 2019-02-01 08:01:39 -08:00
sound Prep patches + headers for the mei-hdcp/i915 component interfaces 2019-02-20 11:53:48 +02:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-02-15 08:00:11 -08:00
usr user/Makefile: Fix typo and capitalization in comment section 2018-12-11 00:18:03 +09:00
virt KVM/ARM fixes for 5.0: 2019-02-13 19:39:24 +01:00
.clang-format clang-format: Update .clang-format with the latest for_each macro list 2019-01-19 19:26:06 +01:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: Add support for DT binding schema checks 2018-12-13 09:41:32 -06:00
.mailmap A few early MIPS fixes for 4.21: 2019-01-05 12:48:25 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS Add CREDITS entry for Shaohua Li 2019-01-04 14:27:09 -07:00
Kbuild kbuild: use assignment instead of define ... endef for filechk_* rules 2019-01-06 10:22:35 +09:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS Merge https://gitlab.freedesktop.org/drm/msm into drm-next 2019-02-20 12:16:37 +10:00
Makefile Linux 5.0-rc7 2019-02-17 18:46:40 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

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.