On Mon, Apr 24, 2017 at 10:16:38PM +0200, Lukas Wunner wrote:
> On Mon, Apr 24, 2017 at 05:27:43PM +0300, Imre Deak wrote:
> > Since
> >
> > commit bac2a909a096c9110525c18cbb8ce73c660d5f71
> > Author: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> > Date: Wed Jan 21 02:17:42 2015 +0100
> >
> > PCI / PM: Avoid resuming PCI devices during system suspend
>
> This is not the commit you are looking for. :-) See below.
>
>
> > PCI devices will default to allowing the system suspend complete
> > optimization where devices are not woken up during system suspend if
> > they were already runtime suspended. This however breaks the i915/HDA
> > drivers for two reasons:
> >
> > - The i915 driver has system suspend specific steps that it needs to
> > run, that bring the device to a different state than its runtime
> > suspended state.
> >
> > - The HDA driver's suspend handler requires power that it will request
> > from the i915 driver's power domain handler. This in turn requires the
> > i915 driver to runtime resume itself, but this won't be possible if the
> > suspend complete optimization is in effect: in this case the i915
> > runtime PM is disabled and trying to get an RPM reference returns
> > -EACCESS.
>
> Hm, sounds like something that needs to be solved with device_links.
>
>
> >
> > Solve this by requiring the PCI/PM core to resume the device during
> > system suspend which in effect disables the suspend complete optimization.
> >
> > One possibility for this bug staying hidden for so long is that the
> > optimization for a device is disabled if it's disabled for any of its
> > children devices. i915 may have a backlight device as its child which
> > doesn't support runtime PM and so doesn't allow the optimization either.
> > So if this backlight device got registered the bug stayed hidden.
>
> No, the reason this hasn't popped up earlier is because direct_complete
> has only been enabled for DRM devices for a few months now, to be specific
> since
>
> commit d14d2a8453d650bea32a1c5271af1458cd283a0f
> Author: Lukas Wunner <lukas@xxxxxxxxx>
> Date: Wed Jun 8 12:49:29 2016 +0200
>
> drm: Remove dev_pm_ops from drm_class
>
> which landed in v4.8.
Right, this kept the optimization disabled even after bac2a909a096c91.
It did stay disabled on platforms with a backlight driver registered as
described above.
--Imre
>
> (Sorry for not raising my voice earlier, this patch appeared on my radar
> just now.)
>
> Kind regards,
>
> Lukas
>
> >
> > Credits to Marta, Tomi and David who enabled pstore logging,
> > that caught one instance of this issue across a suspend/
> > resume-to-ram and Ville who rememberd that the optimization was enabled
> > for some devices at one point.
> >
> > The first WARN triggered by the problem:
> >
> > [ 6250.746445] WARNING: CPU: 2 PID: 17384 at drivers/gpu/drm/i915/intel_runtime_pm.c:2846 intel_runtime_pm_get+0x6b/0xd0 [i915]
> > [ 6250.746448] pm_runtime_get_sync() failed: -13
> > [ 6250.746451] Modules linked in: snd_hda_intel i915 vgem snd_hda_codec_hdmi x86_pkg_temp_thermal intel_powerclamp coretemp crct10dif_pclmul crc32_pclmul
> > snd_hda_codec_realtek snd_hda_codec_generic ghash_clmulni_intel e1000e snd_hda_codec snd_hwdep snd_hda_core ptp mei_me pps_core snd_pcm lpc_ich mei prime_
> > numbers i2c_hid i2c_designware_platform i2c_designware_core [last unloaded: i915]
> > [ 6250.746512] CPU: 2 PID: 17384 Comm: kworker/u8:0 Tainted: G U W 4.11.0-rc5-CI-CI_DRM_334+ #1
> > [ 6250.746515] Hardware name: /NUC5i5RYB, BIOS RYBDWi35.86A.0362.2017.0118.0940 01/18/2017
> > [ 6250.746521] Workqueue: events_unbound async_run_entry_fn
> > [ 6250.746525] Call Trace:
> > [ 6250.746530] dump_stack+0x67/0x92
> > [ 6250.746536] __warn+0xc6/0xe0
> > [ 6250.746542] ? pci_restore_standard_config+0x40/0x40
> > [ 6250.746546] warn_slowpath_fmt+0x46/0x50
> > [ 6250.746553] ? __pm_runtime_resume+0x56/0x80
> > [ 6250.746584] intel_runtime_pm_get+0x6b/0xd0 [i915]
> > [ 6250.746610] intel_display_power_get+0x1b/0x40 [i915]
> > [ 6250.746646] i915_audio_component_get_power+0x15/0x20 [i915]
> > [ 6250.746654] snd_hdac_display_power+0xc8/0x110 [snd_hda_core]
> > [ 6250.746661] azx_runtime_resume+0x218/0x280 [snd_hda_intel]
> > [ 6250.746667] pci_pm_runtime_resume+0x76/0xa0
> > [ 6250.746672] __rpm_callback+0xb4/0x1f0
> > [ 6250.746677] ? pci_restore_standard_config+0x40/0x40
> > [ 6250.746682] rpm_callback+0x1f/0x80
> > [ 6250.746686] ? pci_restore_standard_config+0x40/0x40
> > [ 6250.746690] rpm_resume+0x4ba/0x740
> > [ 6250.746698] __pm_runtime_resume+0x49/0x80
> > [ 6250.746703] pci_pm_suspend+0x57/0x140
> > [ 6250.746709] dpm_run_callback+0x6f/0x330
> > [ 6250.746713] ? pci_pm_freeze+0xe0/0xe0
> > [ 6250.746718] __device_suspend+0xf9/0x370
> > [ 6250.746724] ? dpm_watchdog_set+0x60/0x60
> > [ 6250.746730] async_suspend+0x1a/0x90
> > [ 6250.746735] async_run_entry_fn+0x34/0x160
> > [ 6250.746741] process_one_work+0x1f2/0x6d0
> > [ 6250.746749] worker_thread+0x49/0x4a0
> > [ 6250.746755] kthread+0x107/0x140
> > [ 6250.746759] ? process_one_work+0x6d0/0x6d0
> > [ 6250.746763] ? kthread_create_on_node+0x40/0x40
> > [ 6250.746768] ret_from_fork+0x2e/0x40
> > [ 6250.746778] ---[ end trace 102a62fd2160f5e6 ]---
> >
> > v2:
> > - Use the new pci_dev->needs_resume flag, to avoid any overhead during
> > the ->pm_prepare hook. (Rafael)
> >
> > Fixes: bac2a909a096 ("PCI / PM: Avoid resuming PCI devices during system suspend")
> > References: https://bugs.freedesktop.org/show_bug.cgi?id=100378
> > Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> > Cc: Marta Lofstedt <marta.lofstedt@xxxxxxxxx>
> > Cc: David Weinehall <david.weinehall@xxxxxxxxxxxxxxx>
> > Cc: Tomi Sarvela <tomi.p.sarvela@xxxxxxxxx>
> > Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> > Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxx>
> > Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> > Cc: Takashi Iwai <tiwai@xxxxxxx>
> > Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> > Cc: linux-pci@xxxxxxxxxxxxxxx
> > Cc: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
> > Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> (v1)
> > ---
> > drivers/gpu/drm/i915/i915_drv.c | 9 +++++++++
> > 1 file changed, 9 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> > index 8be958f..dd7ce69 100644
> > --- a/drivers/gpu/drm/i915/i915_drv.c
> > +++ b/drivers/gpu/drm/i915/i915_drv.c
> > @@ -1207,6 +1207,15 @@ int i915_driver_load(struct pci_dev *pdev, const struct pci_device_id *ent)
> > goto out_free_priv;
> >
> > pci_set_drvdata(pdev, &dev_priv->drm);
> > + /*
> > + * Disable the system suspend direct complete optimization, which can
> > + * leave the device suspended skipping the driver's suspend handlers
> > + * if the device was already runtime suspended. This is needed due to
> > + * the difference in our runtime and system suspend sequence and
> > + * becaue the HDA driver may require us to enable the audio power
> > + * domain during system suspend.
> > + */
> > + pci_resume_before_suspend(pdev, true);
> >
> > ret = i915_driver_init_early(dev_priv, ent);
> > if (ret < 0)
> > --
> > 2.5.0
> >
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