This is a note to let you know that I've just added the patch titled
drm/i915: Discard previous atomic state on resume if connectors change
to the 4.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-i915-discard-previous-atomic-state-on-resume-if-connectors-change.patch
and it can be found in the queue-4.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From cpaul@xxxxxxxxxx Sat Jun 4 13:43:28 2016
From: Lyude <cpaul@xxxxxxxxxx>
Date: Tue, 31 May 2016 12:49:06 -0400
Subject: drm/i915: Discard previous atomic state on resume if connectors change
To: stable@xxxxxxxxxxxxxxx, Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Lyude <cpaul@xxxxxxxxxx>, Daniel Vetter <daniel.vetter@xxxxxxxxx>, Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>, David Airlie <airlied@xxxxxxxx>, intel-gfx@xxxxxxxxxxxxxxxxxxxxx (open list:INTEL DRM DRIVERS (excluding Poulsbo, Moorestow...), dri-devel@xxxxxxxxxxxxxxxxxxxxx (open list:INTEL DRM DRIVERS (excluding Poulsbo, Moorestow...), linux-kernel@xxxxxxxxxxxxxxx (open list)))
Message-ID: <1464713347-28982-4-git-send-email-cpaul@xxxxxxxxxx>
From: Lyude <cpaul@xxxxxxxxxx>
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before suspending is no longer valid, since it'll still be pointing to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
Changes since v1:
- Move drm_atomic_state_free() call down so we're holding the
appropriate locks when destroying the atomic state
Changes since v2:
- Check that state != NULL before we start accessing it's members
This fix is only required for 4.6 and below. David Airlie's patchseries
for 4.7 to add connector reference counting provides a more proper fix
for this.
Upstream fix: 0552f7651bc2 ("drm/i915/mst: use reference counted
connectors. (v3)")
Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
Signed-off-by: Lyude <cpaul@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/intel_display.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -15958,6 +15958,18 @@ void intel_display_resume(struct drm_dev
retry:
ret = drm_modeset_lock_all_ctx(dev, &ctx);
+ /*
+ * 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 (ret == 0 && state &&
+ state->num_connector != dev->mode_config.num_connector) {
+ drm_atomic_state_free(state);
+ state = NULL;
+ }
+
if (ret == 0 && !setup) {
setup = true;
Patches currently in stable-queue which might be from cpaul@xxxxxxxxxx are
queue-4.6/drm-i915-fbdev-fix-num_connector-references-in-intel_fb_initial_config.patch
queue-4.6/drm-i915-psr-try-to-program-link-training-times-correctly.patch
queue-4.6/drm-fb_helper-fix-references-to-dev-mode_config.num_connector.patch
queue-4.6/drm-i915-discard-previous-atomic-state-on-resume-if-connectors-change.patch
queue-4.6/drm-atomic-verify-connector-funcs-null-when-clearing-states.patch
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