Bug 93441

Summary: [SKL] RPM wakelock ref not held during HW access (check_wm_state->skl_ddb_get_hw_state)
Product: DRI Reporter: Imre Deak <imre.deak>
Component: DRM/IntelAssignee: Intel GFX Bugs mailing list <intel-gfx-bugs>
Status: CLOSED FIXED QA Contact: Intel GFX Bugs mailing list <intel-gfx-bugs>
Severity: critical    
Priority: medium CC: intel-gfx-bugs
Version: DRI git   
Hardware: Other   
OS: All   
Whiteboard:
i915 platform: i915 features:

Description Imre Deak 2015-12-18 15:17:50 UTC 
The WARN below started to appear after adding stricter RPM reference checking asserts. Testcases that triggered this during CI runs; the list may be not exact since we stop reporting errors after the first one (by using WARN_ONCE):

igt@kms_flip@basic-flip-vs-modeset
igt@kms_flip@basic-flip-vs-wf_vblank
igt@kms_pipe_crc_basic@read-crc-pipe-c

[  250.913323] ------------[ cut here ]------------
[  250.913377] WARNING: CPU: 0 PID: 6422 at drivers/gpu/drm/i915/intel_drv.h:1446 gen9_read32+0x336/0x3f0 [i915]()
[  250.913381] RPM wakelock ref not held during HW access
[  250.913385] Modules linked in:
[  250.913389]  i915 ax88179_178a usbnet mii x86_pkg_temp_thermal intel_powerclamp coretemp crct10dif_pclmul crc32_pclmul mei_me mei i2c_hid e1000e ptp pps_core [last unloaded: i915]
[  250.913422] CPU: 0 PID: 6422 Comm: kms_flip Tainted: G     U  W       4.4.0-rc5-gfxbench+ #1
[  250.913426] Hardware name: System manufacturer System Product Name/Z170M-PLUS, BIOS 0408 08/28/2015
[  250.913430]  ffffffffa02e68a0 ffff8802479e39c8 ffffffff813e000c ffff8802479e3a10
[  250.913439]  ffff8802479e3a00 ffffffff810746a1 000000000007027c ffff8802479e3b52
[  250.913447]  000000000007027c ffff8801fb640000 0000000000000001 ffff8802479e3a60
[  250.913455] Call Trace:
[  250.913466]  [<ffffffff813e000c>] dump_stack+0x4e/0x82
[  250.913473]  [<ffffffff810746a1>] warn_slowpath_common+0x81/0xc0
[  250.913478]  [<ffffffff81074727>] warn_slowpath_fmt+0x47/0x50
[  250.913487]  [<ffffffff810c5a3d>] ? trace_hardirqs_on+0xd/0x10
[  250.913528]  [<ffffffffa02596b6>] gen9_read32+0x336/0x3f0 [i915]
[  250.913537]  [<ffffffff81796919>] ? mutex_unlock+0x9/0x10
[  250.913561]  [<ffffffffa0210a32>] skl_ddb_get_hw_state+0xa2/0x160 [i915]
[  250.913605]  [<ffffffffa0269ac3>] check_wm_state+0x43/0x1b0 [i915]
[  250.913650]  [<ffffffffa027a58b>] intel_atomic_commit+0x98b/0x17f0 [i915]
[  250.913699]  [<ffffffff8150ed17>] ? drm_atomic_add_affected_connectors+0x87/0xf0
[  250.913706]  [<ffffffff8150e632>] drm_atomic_commit+0x32/0x50
[  250.913715]  [<ffffffff814eb705>] drm_atomic_helper_set_config+0x75/0xb0
[  250.913726]  [<ffffffff814fd640>] drm_mode_set_config_internal+0x60/0x110
[  250.913733]  [<ffffffff815023d6>] drm_mode_setcrtc+0x186/0x4f0
[  250.913739]  [<ffffffff811844f8>] ? __might_fault+0x48/0xa0
[  250.913761]  [<ffffffff814f450d>] drm_ioctl+0x13d/0x590
[  250.913774]  [<ffffffff81502250>] ? drm_mode_setplane+0x1b0/0x1b0
[  250.913789]  [<ffffffff811c2793>] ? __vfs_read+0x23/0xd0
[  250.913801]  [<ffffffff811d53ec>] do_vfs_ioctl+0x2fc/0x550
[  250.913817]  [<ffffffff811e0e5a>] ? __fget_light+0x6a/0x90
[  250.913829]  [<ffffffff811d567c>] SyS_ioctl+0x3c/0x70
[  250.913846]  [<ffffffff8179a45b>] entry_SYSCALL_64_fastpath+0x16/0x73
[  250.913857] ---[ end trace 69fd11dcfc73e82c ]---
Comment 1 Imre Deak 2016-02-18 14:06:55 UTC 
The fix is merged now, closing:

commit 4d800030238878c1a98d1d3a37a3d673eea661ce
Author: Imre Deak <imre.deak@intel.com>
Date:   Wed Feb 17 16:31:29 2016 +0200

    drm/i915/skl: Ensure HW is powered during DDB HW state readout

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