[Intel-gfx] [PATCH 2/4] drm/i915: Fix POWER_DOMAIN_AUDIO refcounting.

[Daniel Vetter]

On Mon, Jan 16, 2017 at 12:00:46PM +0100, Maarten Lankhorst wrote:
> Op 11-01-17 om 17:13 schreef Daniel Vetter:
> > On Thu, Dec 15, 2016 at 03:29:43PM +0100, Maarten Lankhorst wrote:
> >> If the crtc was brought up with audio before the driver loads,
> >> then crtc_disable will remove a refcount to audio that doesn't exist
> >> before.
> >>
> >> Fortunately we already set power domains on readout, so we can just add
> >> the power domain handling to get_crtc_power_domains, which will update
> >> the power domains correctly in all cases.
> >>
> >> This was found when testing module reload on CI with the crtc enabled,
> >> which resulted in the following warn after module reload + modeset:
> >>
> >> [   24.197041] ------------[ cut here ]------------
> >> [   24.197075] WARNING: CPU: 0 PID: 99 at drivers/gpu/drm/i915/intel_runtime_pm.c:1790 intel_display_power_put+0x134/0x140 [i915]
> >> [   24.197076] Use count on domain AUDIO is already zero
> >> [   24.197098] CPU: 0 PID: 99 Comm: kworker/u8:2 Not tainted 4.9.0-CI-Trybot_393+ #1
> >> [   24.197099] Hardware name:                  /NUC6i5SYB, BIOS SYSKLi35.86A.0042.2016.0409.1246 04/09/2016
> >> [   24.197102] Workqueue: events_unbound async_run_entry_fn
> >> [   24.197105]  ffffc900003c7688 ffffffff81435b35 ffffc900003c76d8 0000000000000000
> >> [   24.197107]  ffffc900003c76c8 ffffffff8107e4d6 000006fe5dc36f28 ffff88025dc30054
> >> [   24.197109]  ffff88025dc36f28 ffff88025dc30000 ffff88025dc30000 0000000000000015
> >> [   24.197110] Call Trace:
> >> [   24.197113]  [<ffffffff81435b35>] dump_stack+0x67/0x92
> >> [   24.197116]  [<ffffffff8107e4d6>] __warn+0xc6/0xe0
> >> [   24.197118]  [<ffffffff8107e53a>] warn_slowpath_fmt+0x4a/0x50
> >> [   24.197149]  [<ffffffffa039b4b4>] intel_display_power_put+0x134/0x140 [i915]
> >> [   24.197187]  [<ffffffffa04217dd>] intel_disable_ddi+0x4d/0x80 [i915]
> >> [   24.197223]  [<ffffffffa03f388f>] intel_encoders_disable.isra.74+0x7f/0x90 [i915]
> >> [   24.197257]  [<ffffffffa03f6c05>] haswell_crtc_disable+0x55/0x170 [i915]
> >> [   24.197292]  [<ffffffffa03fec88>] intel_atomic_commit_tail+0x108/0xfd0 [i915]
> >> [   24.197295]  [<ffffffff810d47c6>] ? __lock_is_held+0x66/0x90
> >> [   24.197330]  [<ffffffffa03fff79>] intel_atomic_commit+0x429/0x560 [i915]
> >> [   24.197332]  [<ffffffff81570186>] ?drm_atomic_add_affected_connectors+0x56/0xf0
> >> [   24.197334]  [<ffffffff8156f726>] drm_atomic_commit+0x46/0x50
> >> [   24.197336]  [<ffffffff81553f87>] restore_fbdev_mode+0x147/0x270
> >> [   24.197337]  [<ffffffff81555bee>] drm_fb_helper_restore_fbdev_mode_unlocked+0x2e/0x70
> >> [   24.197339]  [<ffffffff81555aa8>] drm_fb_helper_set_par+0x28/0x50
> >> [   24.197374]  [<ffffffffa041c7d3>] intel_fbdev_set_par+0x13/0x70 [i915]
> >> [   24.197376]  [<ffffffff8149e07a>] fbcon_init+0x57a/0x600
> >> [   24.197379]  [<ffffffff81514b71>] visual_init+0xd1/0x130
> >> [   24.197381]  [<ffffffff8151603c>] do_bind_con_driver+0x1bc/0x3a0
> >> [   24.197384]  [<ffffffff81516521>] do_take_over_console+0x111/0x180
> >> [   24.197386]  [<ffffffff8149e152>] do_fbcon_takeover+0x52/0xb0
> >> [   24.197387]  [<ffffffff814a12c3>] fbcon_event_notify+0x723/0x850
> >> [   24.197390]  [<ffffffff810a4830>] ?__blocking_notifier_call_chain+0x30/0x70
> >> [   24.197392]  [<ffffffff810a44a4>] notifier_call_chain+0x34/0xa0
> >> [   24.197394]  [<ffffffff810a4848>] __blocking_notifier_call_chain+0x48/0x70
> >> [   24.197397]  [<ffffffff810a4881>] blocking_notifier_call_chain+0x11/0x20
> >> [   24.197398]  [<ffffffff814a4556>] fb_notifier_call_chain+0x16/0x20
> >> [   24.197400]  [<ffffffff814a678c>] register_framebuffer+0x24c/0x330
> >> [   24.197402]  [<ffffffff815558d9>] drm_fb_helper_initial_config+0x219/0x3c0
> >> [   24.197436]  [<ffffffffa041d373>] intel_fbdev_initial_config+0x13/0x30 [i915]
> >> [   24.197438]  [<ffffffff810a5d44>] async_run_entry_fn+0x34/0x140
> >> [   24.197440]  [<ffffffff8109c26c>] process_one_work+0x1ec/0x6b0
> >> [   24.197442]  [<ffffffff8109c1e6>] ? process_one_work+0x166/0x6b0
> >> [   24.197445]  [<ffffffff8109c779>] worker_thread+0x49/0x490
> >> [   24.197447]  [<ffffffff8109c730>] ? process_one_work+0x6b0/0x6b0
> >> [   24.197448]  [<ffffffff810a2a9b>] kthread+0xeb/0x110
> >> [   24.197451]  [<ffffffff810a29b0>] ? kthread_park+0x60/0x60
> >> [   24.197453]  [<ffffffff818241a7>] ret_from_fork+0x27/0x40
> >> [   24.197476] ---[ end trace bda64b683b8e8162 ]---
> >>
> >> Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> > Do we still need this with patch 3? I know it'd be nice if we could
> > faithfully restore any state we can also program, but then that's also a
> > lot of complexity ...
> >
> > Otoh patch 3 means we'll stop testing a lot of the fastboot code while
> > reloading the driver. But then that's been the thing in the past, and as
> > long as we still boot up we have at least some test coverage fo the
> > fastboot code (I'm mostly concerned about the plane/buffer readout code,
> > since that's not covered by the state checker).
> >
> > But for now I'd say let's just go with patch 3 only.
> We don't need this patch, but it makes the audio power domain tracked
> like all other power domains. It's a nice cleanup in general and I would
> like it even without the rest of the series. Could otherwise be merged
> through the intel tree through.

Hm, count me convinced.

Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch