[Intel-gfx] [PATCH v2] drm/i915: Avoid busy-spinning on VLV_GLTC_PW_STATUS mmio
Chris Wilson
chris at chris-wilson.co.uk
Fri Apr 21 13:58:15 UTC 2017
The busy-spin, as the first stage of intel_wait_for_register(), is
currently under suspicion for causing:
[ 62.034926] NMI watchdog: Watchdog detected hard LOCKUP on cpu 1
[ 62.034928] Modules linked in: i2c_dev i915 intel_gtt drm_kms_helper prime_numbers
[ 62.034932] CPU: 1 PID: 183 Comm: kworker/1:2 Not tainted 4.11.0-rc7+ #471
[ 62.034933] Hardware name: / , BIOS PYBSWCEL.86A.0027.2015.0507.1758 05/07/2015
[ 62.034934] Workqueue: pm pm_runtime_work
[ 62.034936] task: ffff880275a04ec0 task.stack: ffffc900002d8000
[ 62.034936] RIP: 0010:__intel_wait_for_register_fw+0x77/0x1a0 [i915]
[ 62.034937] RSP: 0018:ffffc900002dbc38 EFLAGS: 00000082
[ 62.034939] RAX: ffffc90003530094 RBX: 0000000000130094 RCX: 0000000000000001
[ 62.034940] RDX: 00000000000000a1 RSI: ffff88027fd15e58 RDI: 0000000000000000
[ 62.034941] RBP: ffffc900002dbc78 R08: 0000000000000002 R09: 0000000000000000
[ 62.034942] R10: ffffc900002dbc18 R11: ffff880276429dd0 R12: ffff8802707c0000
[ 62.034943] R13: 00000000000000a0 R14: 0000000000000000 R15: 00000000fffefc10
[ 62.034945] FS: 0000000000000000(0000) GS:ffff88027fd00000(0000) knlGS:0000000000000000
[ 62.034945] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 62.034947] CR2: 00007ffd3cd98ff8 CR3: 0000000274c19000 CR4: 00000000001006e0
[ 62.034947] Call Trace:
[ 62.034948] intel_wait_for_register+0x77/0x140 [i915]
[ 62.034949] vlv_suspend_complete+0x23/0x5b0 [i915]
[ 62.034950] intel_runtime_suspend+0x16c/0x2a0 [i915]
[ 62.034950] pci_pm_runtime_suspend+0x50/0x180
[ 62.034951] ? pci_pm_runtime_resume+0xa0/0xa0
[ 62.034952] __rpm_callback+0xc5/0x210
[ 62.034953] rpm_callback+0x1f/0x80
[ 62.034953] ? pci_pm_runtime_resume+0xa0/0xa0
[ 62.034954] rpm_suspend+0x118/0x580
[ 62.034955] pm_runtime_work+0x64/0x90
[ 62.034956] process_one_work+0x1bb/0x3e0
[ 62.034956] worker_thread+0x46/0x4f0
[ 62.034957] ? __schedule+0x18b/0x610
[ 62.034958] kthread+0xff/0x140
[ 62.034958] ? process_one_work+0x3e0/0x3e0
[ 62.034959] ? kthread_create_on_node+
and related hard lockups in CI for byt and bsw.
Note this effectively reverts commits 41ce405e6894 and b27366958869
("drm/i915: Convert wait_for(I915_READ(reg)) to intel_wait_for_register()")
v2: Convert bool allow into a u32 mask for clarity and repeat the
comment on vlv rc6 timing to justify the 3ms timeout used for the wait (Ville)
Fixes: 41ce405e6894 ("drm/i915: Convert wait_for(I915_READ(reg)) to intel_wait_for_register()")
Fixes: b27366958869 ("drm/i915: Convert wait_for(I915_READ(reg)) to intel_wait_for_register()")
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=100718
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Cc: Tomi Sarvela <tomi.p.sarvela at intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
drivers/gpu/drm/i915/i915_drv.c | 46 +++++++++++++++++++++--------------------
1 file changed, 24 insertions(+), 22 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index e4f902f61e57..dc48eae4072c 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -2179,6 +2179,20 @@ static void vlv_restore_gunit_s0ix_state(struct drm_i915_private *dev_priv)
I915_WRITE(VLV_GUNIT_CLOCK_GATE2, s->clock_gate_dis2);
}
+static int vlv_wait_for_pw_status(struct drm_i915_private *dev_priv,
+ u32 mask, u32 val)
+{
+ /* The HW does not like us polling for PW_STATUS frequently, so
+ * use the sleeping loop rather than risk the busy spin within
+ * intel_wait_for_register().
+ *
+ * Transitioning between RC6 states should be at most 2ms (see
+ * valleyview_enable_rps) so use a 3ms timeout.
+ */
+ return wait_for((I915_READ_NOTRACE(VLV_GTLC_PW_STATUS) & mask) == val,
+ 3);
+}
+
int vlv_force_gfx_clock(struct drm_i915_private *dev_priv, bool force_on)
{
u32 val;
@@ -2207,8 +2221,9 @@ int vlv_force_gfx_clock(struct drm_i915_private *dev_priv, bool force_on)
static int vlv_allow_gt_wake(struct drm_i915_private *dev_priv, bool allow)
{
+ u32 mask;
u32 val;
- int err = 0;
+ int err;
val = I915_READ(VLV_GTLC_WAKE_CTRL);
val &= ~VLV_GTLC_ALLOWWAKEREQ;
@@ -2217,45 +2232,32 @@ static int vlv_allow_gt_wake(struct drm_i915_private *dev_priv, bool allow)
I915_WRITE(VLV_GTLC_WAKE_CTRL, val);
POSTING_READ(VLV_GTLC_WAKE_CTRL);
- err = intel_wait_for_register(dev_priv,
- VLV_GTLC_PW_STATUS,
- VLV_GTLC_ALLOWWAKEACK,
- allow,
- 1);
+ mask = VLV_GTLC_ALLOWWAKEACK;
+ val = allow ? mask : 0;
+
+ err = vlv_wait_for_pw_status(dev_priv, mask, val);
if (err)
DRM_ERROR("timeout disabling GT waking\n");
return err;
}
-static int vlv_wait_for_gt_wells(struct drm_i915_private *dev_priv,
- bool wait_for_on)
+static void vlv_wait_for_gt_wells(struct drm_i915_private *dev_priv,
+ bool wait_for_on)
{
u32 mask;
u32 val;
- int err;
mask = VLV_GTLC_PW_MEDIA_STATUS_MASK | VLV_GTLC_PW_RENDER_STATUS_MASK;
val = wait_for_on ? mask : 0;
- if ((I915_READ(VLV_GTLC_PW_STATUS) & mask) == val)
- return 0;
-
- DRM_DEBUG_KMS("waiting for GT wells to go %s (%08x)\n",
- onoff(wait_for_on),
- I915_READ(VLV_GTLC_PW_STATUS));
/*
* RC6 transitioning can be delayed up to 2 msec (see
* valleyview_enable_rps), use 3 msec for safety.
*/
- err = intel_wait_for_register(dev_priv,
- VLV_GTLC_PW_STATUS, mask, val,
- 3);
- if (err)
+ if (vlv_wait_for_pw_status(dev_priv, mask, val))
DRM_ERROR("timeout waiting for GT wells to go %s\n",
onoff(wait_for_on));
-
- return err;
}
static void vlv_check_no_gt_access(struct drm_i915_private *dev_priv)
@@ -2276,7 +2278,7 @@ static int vlv_suspend_complete(struct drm_i915_private *dev_priv)
* Bspec defines the following GT well on flags as debug only, so
* don't treat them as hard failures.
*/
- (void)vlv_wait_for_gt_wells(dev_priv, false);
+ vlv_wait_for_gt_wells(dev_priv, false);
mask = VLV_GTLC_RENDER_CTX_EXISTS | VLV_GTLC_MEDIA_CTX_EXISTS;
WARN_ON((I915_READ(VLV_GTLC_WAKE_CTRL) & mask) != mask);
--
2.11.0
More information about the Intel-gfx
mailing list