Yeah airlied said the same thing. This patch is more intended for just 4.6 since
the refcounting patch isn't very likely to get into 4.6.
On Tue, 2016-05-03 at 16:29 +0200, Daniel Vetter wrote:
> On Tue, May 03, 2016 at 10:03:40AM -0400, Lyude wrote:
> >
> > If an MST device is disconnected while the machine is suspended, the
> > number of connectors will change as well after we call
> > intel_dp_mst_resume(). This means that any previous atomic state we had
> > before suspending is no longer valid, since it'll still be pointing to
> > missing connectors. We need to check for this before committing the
> > state, otherwise we'll kernel panic on resume whenever if any MST
> > display was disconnected before we started resuming:
> >
> > BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
> > IP: [<ffffffffa01588ef>] drm_atomic_helper_check_modeset+0x29f/0xb40
> > [drm_kms_helper]
> > Call Trace:
> > [<ffffffffa02354f4>] intel_atomic_check+0x34/0x1180 [i915]
> > [<ffffffff810e6c3f>] ? mark_held_locks+0x6f/0xa0
> > [<ffffffff810e6d99>] ? trace_hardirqs_on_caller+0x129/0x1b0
> > [<ffffffffa00ff1d2>] drm_atomic_check_only+0x192/0x620 [drm]
> > [<ffffffff813ee001>] ? pci_pm_thaw+0x21/0x90
> > [<ffffffffa00ff677>] drm_atomic_commit+0x17/0x60 [drm]
> > [<ffffffffa023e0ad>] intel_display_resume+0xbd/0x160 [i915]
> > [<ffffffff813ee070>] ? pci_pm_thaw+0x90/0x90
> > [<ffffffffa01b60d8>] i915_drm_resume+0xd8/0x160 [i915]
> > [<ffffffffa01b6185>] i915_pm_resume+0x25/0x30 [i915]
> > [<ffffffff813ee0d4>] pci_pm_resume+0x64/0xa0
> > [<ffffffff814d9ea0>] dpm_run_callback+0x90/0x190
> > [<ffffffff814da455>] device_resume+0xd5/0x1f0
> > [<ffffffff814da58d>] async_resume+0x1d/0x50
> > [<ffffffff810b6718>] async_run_entry_fn+0x48/0x150
> > [<ffffffff810acc19>] process_one_work+0x1e9/0x5c0
> > [<ffffffff810acb96>] ? process_one_work+0x166/0x5c0
> > [<ffffffff810ad038>] worker_thread+0x48/0x4e0
> > [<ffffffff810acff0>] ? process_one_work+0x5c0/0x5c0
> > [<ffffffff810b3794>] kthread+0xe4/0x100
> > [<ffffffff81742672>] ret_from_fork+0x22/0x50
> > [<ffffffff810b36b0>] ? kthread_create_on_node+0x200/0x200
> >
> > Cc: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: Lyude <cpaul@xxxxxxxxxx>
> This should be addressed by the connector refcounting fixes Dave Airlie
> has for 4.7 (not all merged yet though). Can you please retest with those?
> -Daniel
>
> >
> > ---
> > drivers/gpu/drm/i915/intel_display.c | 11 +++++++++++
> > 1 file changed, 11 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_display.c
> > b/drivers/gpu/drm/i915/intel_display.c
> > index 6e0d828..252c06c 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -15945,6 +15945,17 @@ void intel_display_resume(struct drm_device *dev)
> > dev_priv->modeset_restore_state = NULL;
> >
> > /*
> > + * With MST, the number of connectors can change between suspend
> > and
> > + * resume, which means that the state we want to restore might now
> > be
> > + * impossible to use since it'll be pointing to non-existant
> > + * connectors.
> > + */
> > + if (state->num_connector != dev->mode_config.num_connector) {
> > + drm_atomic_state_free(state);
> > + state = NULL;
> > + }
> > +
> > + /*
> > * This is a cludge because with real atomic modeset
> > mode_config.mutex
> > * won't be taken. Unfortunately some probed state like
> > * audio_codec_enable is still protected by mode_config.mutex, so
> > lock
> > --
> > 2.5.5
> >
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html