From 781cc76e0c2469cb7ac12ba238a4ea006978e321 Mon Sep 17 00:00:00 2001
From: Daniel Vetter <daniel.vetter@ffwll.ch>
Date: Tue, 8 Aug 2017 10:08:26 +0200
Subject: [PATCH] drm/i915: Avoid the gpu reset vs. modeset deadlock
Git-commit: 781cc76e0c2469cb7ac12ba238a4ea006978e321
Patch-mainline: v4.13-rc6
References: FATE#322643 bsc#1055900
No-fix: 97154ec242c14f646a3ab3b4da8f838d197f300d
... using the biggest hammer we have. This is essentially a weaponized
version of the timeout-based wedging Chris added in
commit 36703e79a982c8ce5a8e43833291f2719e92d0d1
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Thu Jun 22 11:56:25 2017 +0100
drm/i915: Break modeset deadlocks on reset
Because defense-in-depth is good it's good to still have both. Also
note that with the locking change we can now restrict this a lot (old
gpus and special testing only), so this doesn't kill the TDR benefits
on at least anything remotely modern.
And futuremore with a few tricks it should be possible to make a much
more educated guess about whether an atomic commit is stuck waiting on
the gpu (atomic_t counting the pending i915_sw_fence used by the
atomic modeset code should do it), so we can improve this.
But for now just start with something that is guaranteed to recover
faster, for much better CI througput.
This defacto reverts TDR on these platforms, but there's not really a
single commit to specify as the sole offender.
V2: Add a debug message to explain what's going on. We can't DRM_ERROR
because that spams CI. And the timeout based fallback still prints a
DRM_ERROR, in case something goes wrong.
V3: Fix comment layout (Michel)
Fixes: 4680816be336 ("drm/i915: Wait first for submission, before waiting for request completion")
Fixes: 221fe7994554 ("drm/i915: Perform a direct reset of the GPU from the waiter")
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> (v2)
Cc: Michel Thierry <michel.thierry@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> (v2)
Reviewed-by: Michel Thierry <michel.thierry@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170808080828.23650-1-daniel.vetter@ffwll.ch
(cherry picked from commit 97154ec242c14f646a3ab3b4da8f838d197f300d)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/gpu/drm/i915/intel_display.c | 7 +++++++
1 file changed, 7 insertions(+)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3485,6 +3485,13 @@ void intel_prepare_reset(struct drm_i915
!gpu_reset_clobbers_display(dev_priv))
return;
+ /* We have a modeset vs reset deadlock, defensively unbreak it.
+ *
+ * FIXME: We can do a _lot_ better, this is just a first iteration.
+ */
+ i915_gem_set_wedged(dev_priv);
+ DRM_DEBUG_DRIVER("Wedging GPU to avoid deadlocks with pending modeset updates\n");
+
/*
* Need mode_config.mutex so that we don't
* trample ongoing ->detect() and whatnot.